Kukula kwa magwiridwe antchito apamwamba, masensa onyamula komanso ocheperako akukulirakulira m'malo owunikira zachilengedwe, chitetezo, zowunikira zamankhwala ndi ulimi.Pakati pa zida zosiyanasiyana zodziwira, metal-oxide-semiconductor (MOS) chemo-resistive gas sensors ndi zosankha zodziwika kwambiri pazamalonda chifukwa cha kukhazikika kwawo, kutsika mtengo, komanso kumva kwambiri.Imodzi mwa njira zofunika kwambiri zopititsira patsogolo ntchito ya sensa ndi kupanga ma nanosized MOS-based heterojunctions (hetero-nanostructured MOS) kuchokera ku MOS nanomaterials.Komabe, kachipangizo kakang'ono ka heteronanostructured MOS sensor ndi kosiyana ndi kachipangizo kamodzi ka MOS, chifukwa ndizovuta kwambiri.Sensa imakhudzidwa ndi magawo osiyanasiyana, kuphatikiza momwe zinthu ziliri komanso momwe zimapangidwira (monga kukula kwambewu, kachulukidwe kachilema, ndi malo opanda okosijeni), kutentha kwa magwiridwe antchito, ndi kapangidwe kachipangizo.Ndemangayi ikupereka malingaliro angapo opangira ma sensor apamwamba a gasi powunika momwe ma sensor a MOS amapangidwira mosiyanasiyana.Kuonjezera apo, chikoka cha mawonekedwe a geometric a chipangizocho, chotsimikiziridwa ndi mgwirizano pakati pa zinthu zowonongeka ndi electrode yogwira ntchito, ikukambidwa.Kuti muphunzire kachitidwe ka sensa mwadongosolo, nkhaniyi ikuwonetsa ndikukambirana momwe zimagwirira ntchito pazida zitatu zomwe zimagwiritsidwa ntchito potengera ma heteronanostructured materials.Kuwunikaku kudzakhala chiwongolero kwa owerenga amtsogolo omwe amaphunzira njira zomvera za masensa a gasi ndikupanga masensa apamwamba kwambiri.
Kuwonongeka kwa mpweya ndi vuto lalikulu lomwe likukulirakulira komanso vuto lalikulu la chilengedwe padziko lonse lapansi lomwe likuwopseza moyo wa anthu ndi zamoyo.Kukoka mpweya woipitsa mpweya kungayambitse mavuto ambiri azaumoyo monga matenda opuma, khansa ya m'mapapo, khansa ya m'magazi ngakhale kufa msanga1,2,3,4.Kuchokera mu 2012 mpaka 2016, anthu mamiliyoni ambiri anafa chifukwa cha kuwonongeka kwa mpweya, ndipo chaka chilichonse, anthu mabiliyoni ambiri amakumana ndi mpweya woipa5.Chifukwa chake, ndikofunikira kupanga masensa a gasi omwe amatha kunyamula komanso ocheperako omwe angapereke mayankho anthawi yeniyeni komanso magwiridwe antchito apamwamba (mwachitsanzo, kukhudzika, kusankha, kukhazikika, kuyankha ndi kuchira).Kuphatikiza pa kuyang'anira zachilengedwe, zowunikira mpweya zimagwira ntchito yofunika kwambiri pachitetezo6,7,8, diagnostics zachipatala9,10, aquaculture11 ndi madera ena12.
Mpaka pano, masensa angapo otengera gasi otengera njira zosiyanasiyana zowonera adayambitsidwa, monga optical13,14,15,16,17,18, electrochemical19,20,21,22 ndi sensor resistive sensors23,24.Pakati pawo, metal-oxide-semiconductor (MOS) chemical resistive sensors ndizodziwika kwambiri pazamalonda chifukwa cha kukhazikika kwawo komanso mtengo wotsika25,26.Kusakanizika koyipa kumatha kuzindikirika pongozindikira kusintha kwa kukana kwa MOS.Kumayambiriro kwa zaka za m'ma 1960, zida zoyamba za gasi zolimbana ndi chemo zotengera mafilimu opyapyala a ZnO zidanenedwa, zomwe zinapangitsa chidwi chachikulu pakupeza gasi27,28.Masiku ano, ma MOS osiyanasiyana amagwiritsidwa ntchito ngati zida zomwe zimakhudzidwa ndi mpweya, ndipo amatha kugawidwa m'magulu awiri kutengera momwe alili: n-mtundu wa MOS wokhala ndi ma elekitironi monga onyamulira ambiri komanso p-mtundu wa MOS wokhala ndi mabowo monga omwe amanyamula ambiri.kulipira zonyamulira.Kawirikawiri, mtundu wa p-MOS ndi wotchuka kwambiri kusiyana ndi mtundu wa n-MOS chifukwa kuyankha kwamtundu wa p-mtundu wa MOS (Sp) kumakhala kofanana ndi mzere wamtundu wa n-mtundu wa MOS (\(S_p = \sqrt { S_n}\ ) ) pamalingaliro omwewo (mwachitsanzo, mawonekedwe a morphological omwewo komanso kusintha komweko pakupindika kwa magulu mumlengalenga) 29,30.Komabe, masensa amtundu umodzi wa MOS amakumanabe ndi mavuto monga kuchepa kwa malire ozindikira, kukhudzika kochepa komanso kusankhidwa muzogwiritsa ntchito.Nkhani zosankha zitha kuthetsedwa pamlingo wina popanga masensa osiyanasiyana (otchedwa "mphuno zamagetsi") ndikuphatikiza ma aligorivimu osanthula ma computational monga training vector quantization (LVQ), principal component analysis (PCA), and partial little squares (PLS) analysis31 , 32. mwachitsanzo MOS40,41,42 , noble metal nanoparticles (NPs))43,44, carbon nanomaterials45,46 and conductive polymers47,48) kupanga nanoscale heterojunctions (ie, heteronanostructured MOS) ndi njira zina zokondedwa zothetsera mavuto omwe ali pamwambawa.Poyerekeza ndi mafilimu amtundu wamtundu wa MOS, MOS yotsika kwambiri yokhala ndi malo otalikirapo amatha kupangitsa kuti pakhale malo opangira mpweya komanso kuwongolera kufalikira kwa gasi36,37,49.Kuonjezera apo, mapangidwe a heteronanostructures opangidwa ndi MOS amatha kupititsa patsogolo kayendedwe ka zonyamulira pa heterointerface, zomwe zimapangitsa kusintha kwakukulu kwa kukana chifukwa cha ntchito zosiyana siyana50,51,52.Kuonjezera apo, zina mwazogwiritsira ntchito mankhwala (mwachitsanzo, ntchito zochititsa chidwi ndi synergistic surface reactions) zomwe zimachitika popanga mapangidwe a MOS heteronanostructures amathanso kupititsa patsogolo ntchito ya sensa. Sensa ya sensa, masensa amakono a chemo-resistive amagwiritsa ntchito kuyesa ndi zolakwika, zomwe zimatenga nthawi komanso zopanda ntchito.Chifukwa chake, ndikofunikira kumvetsetsa makina omvera a masensa a gasi a MOS chifukwa amatha kuwongolera kapangidwe ka masensa apamwamba kwambiri.
M'zaka zaposachedwa, masensa a gasi a MOS apangidwa mwachangu ndipo malipoti ena adasindikizidwa pa MOS nanostructures55,56,57, ma sensor a gasi kutentha kwachipinda58,59, zida zapadera za MOS sensor60,61,62 ndi ma sensor apadera a gasi63.Ndemanga yowunikira mu Ndemanga Zina ikuyang'ana pa kufotokozera njira yowonetsera mpweya wamagetsi okhudzana ndi thupi ndi mankhwala a MOS, kuphatikizapo ntchito ya mpweya wa oxygen 64 , udindo wa heteronanostructures 55, 65 ndi kusamutsidwa kwa malipiro pa heterointerfaces 66. , magawo ena ambiri amakhudza magwiridwe antchito a sensa, kuphatikiza heterostructure, kukula kwa tirigu, kutentha kwa ntchito, kachulukidwe kachilema, mwayi wa okosijeni, ngakhale ndege zotseguka za kristalo zazinthu tcheru25,67,68,69,70,71.72, 73. Komabe, (zosatchulidwa kawirikawiri) mawonekedwe a geometric a chipangizocho, chotsimikiziridwa ndi mgwirizano pakati pa zinthu zomveka ndi electrode yogwira ntchito, imakhudzanso kwambiri kukhudzidwa kwa sensor74,75,76 (onani gawo 3 kuti mudziwe zambiri) .Mwachitsanzo, Kumar et al.77 inanena za masensa awiri a gasi kutengera zinthu zomwezo (mwachitsanzo, masensa agasi amitundu iwiri kutengera TiO2@NiO ndi NiO@TiO2) ndipo adawona kusintha kosiyana kwa NH3 kukana kwa gasi chifukwa cha ma geometries a zida zosiyanasiyana.Choncho, pofufuza makina opangira mpweya, ndikofunika kuganizira momwe chipangizocho chimapangidwira.Mukuwunikaku, olembawo amayang'ana kwambiri njira zodziwira za MOS zamitundu yosiyanasiyana ya nanostructures ndi zida za zida.Tikukhulupirira kuti ndemangayi ikhoza kukhala chitsogozo kwa owerenga omwe akufuna kumvetsetsa ndi kusanthula njira zodziwira mpweya ndipo angathandize kuti pakhale chitukuko cha magetsi apamwamba kwambiri amtsogolo.
Pa mkuyu.1a ikuwonetsa mtundu woyambira wamakina owonera gasi otengera MOS imodzi.Pamene kutentha kumakwera, ma adsorption a oxygen (O2) mamolekyu pa MOS adzakopa ma elekitironi kuchokera ku MOS ndikupanga mitundu ya anionic (monga O2- ndi O-).Kenaka, electron depletion layer (EDL) ya MOS yamtundu wa n kapena MOS yamtundu wa n-kapena HAL ya mtundu wa p-mtundu wa MOS imapangidwa pamwamba pa MOS 15, 23, 78. Kuyanjana pakati pa O2 ndi MOS imapangitsa gulu la conduction la pamwamba pa MOS kugwada mmwamba ndikupanga chotchinga chomwe chingatheke.Pambuyo pake, sensa ikakumana ndi mpweya womwe mukufuna, mpweya womwe umakhala pamwamba pa MOS umakhudzidwa ndi mitundu ya okosijeni ya ionic, mwina kukopa ma electron (oxidizing gas) kapena kupereka ma electron (kuchepetsa mpweya).Kusintha kwa ma elekitironi pakati pa gasi womwe mukufuna ndi MOS kumatha kusintha m'lifupi mwa EDL kapena HAL30,81 zomwe zimapangitsa kuti pakhale kusintha kwamphamvu kwa sensor ya MOS.Mwachitsanzo, pofuna kuchepetsa mpweya, ma electron adzasamutsidwa kuchokera ku mpweya wochepetsera kupita ku MOS yamtundu wa n, zomwe zimapangitsa kuti EDL ikhale yochepa komanso yotsika kwambiri, yomwe imatchedwa n-type sensor khalidwe.Mosiyana ndi zimenezi, pamene p-mtundu wa MOS umakhala ndi mpweya wochepetsera womwe umatsimikizira khalidwe la p-type sensitivity, HAL imachepa ndipo kukana kumawonjezeka chifukwa cha zopereka za electron.Kwa mpweya wa oxidizing, kuyankha kwa sensa kumasiyana ndi kuchepetsa mpweya.
Njira zodziwira zoyambira za n-mtundu ndi p-mtundu wa MOS pochepetsera komanso kutulutsa mpweya wa okosijeni b Zinthu zazikuluzikulu ndi ma physico-chemical kapena zinthu zomwe zimakhudzidwa ndi semiconductor gas sensor 89
Kupatula njira yodziwikiratu, njira zodziwira mpweya zomwe zimagwiritsidwa ntchito pamasensa agasi ndizovuta kwambiri.Mwachitsanzo, kugwiritsidwa ntchito kwenikweni kwa sensa ya gasi kuyenera kukwaniritsa zofunikira zambiri (monga kukhudzidwa, kusankha, ndi kukhazikika) malingana ndi zosowa za wogwiritsa ntchito.Zofunikira izi zimagwirizana kwambiri ndi thupi ndi mankhwala azinthu zomveka.Mwachitsanzo, Xu et al.71 adawonetsa kuti masensa opangidwa ndi SnO2 amapeza chidwi kwambiri pamene kristalo (d) ndi wofanana kapena kuchepera kuwirikiza kutalika kwa Debye (λD) kwa SnO271.Pamene d ≤ 2λD, SnO2 yatha kwathunthu pambuyo pa kutsatsa kwa mamolekyu a O2, ndipo kuyankha kwa sensa ku mpweya wochepetsera kumakhala kwakukulu.Kuphatikiza apo, magawo ena osiyanasiyana amatha kukhudza magwiridwe antchito a sensa, kuphatikiza kutentha kwa magwiridwe antchito, zolakwika za kristalo, komanso ngakhale magalasi owonekera azinthu zomvera.Makamaka, chikoka cha kutentha kwa ntchito chikufotokozedwa ndi mpikisano wotheka pakati pa mitengo ya adsorption ndi desorption ya gasi yomwe mukufuna, komanso reactivity pamwamba pakati pa mamolekyu a adsorbed gas ndi oxygen particles4,82.Zotsatira za zolakwika za kristalo zimagwirizana kwambiri ndi zomwe zili m'malo a oxygen [83, 84].Kugwira ntchito kwa sensa kungakhudzidwenso ndi mawonekedwe osiyanasiyana a nkhope za kristalo67,85,86,87.Ndege zotsegula zamakristali zokhala ndi kachulukidwe kakang'ono zimawulula ma cations achitsulo osalumikizana omwe ali ndi mphamvu zapamwamba, zomwe zimalimbikitsa kutsatsa kwapamtunda ndikuchitanso88.Gulu 1 limatchula zinthu zingapo zofunika komanso njira zomwe zimayendera bwino.Chifukwa chake, posintha magawo azinthu izi, magwiridwe antchito amatha kuwongolera, ndipo ndikofunikira kudziwa zinthu zazikulu zomwe zimakhudza magwiridwe antchito a sensor.
Yamazoe89 ndi Shimanoe et al.68,71 adachita maphunziro angapo pamalingaliro amalingaliro amalingaliro a sensa ndipo adapereka zinthu zitatu zodziyimira pawokha zomwe zimakhudza magwiridwe antchito a sensa, makamaka receptor ntchito, transducer ntchito, ndi zofunikira (mkuyu 1b)..Ntchito yolandirira imatanthawuza kuthekera kwa pamwamba pa MOS kulumikizana ndi mamolekyu a mpweya.Ntchitoyi ikugwirizana kwambiri ndi mankhwala a MOS ndipo ikhoza kusinthidwa kwambiri poyambitsa ovomerezeka akunja (mwachitsanzo, NPs zachitsulo ndi MOS zina).Ntchito ya transducer imatanthawuza kuthekera kosintha zomwe zimachitika pakati pa mpweya ndi MOS pamwamba kukhala chizindikiro chamagetsi cholamulidwa ndi malire ambewu a MOS.Chifukwa chake, magwiridwe antchito amakhudzidwa kwambiri ndi kukula kwa tinthu ta MOC ndi kuchuluka kwa zolandilira zakunja.Katoch et al.90 adanenanso kuti kuchepetsa kukula kwa tirigu kwa ZnO-SnO2 nanofibrils kunapangitsa kuti pakhale ma heterojunctions ambiri komanso kuwonjezeka kwa sensa, mogwirizana ndi ntchito ya transducer.Wang et al.91 anayerekezera kukula kwambewu zosiyanasiyana za Zn2GeO4 ndipo anawonetsa kuwonjezeka kwa 6.5 kwa mphamvu ya sensa pambuyo poyambitsa malire a tirigu.Utility ndi chinthu china chofunikira cha sensa chomwe chimafotokoza kupezeka kwa gasi kumayendedwe amkati a MOS.Ngati mamolekyu a mpweya sangathe kulowa ndikuchitapo kanthu ndi MOS yamkati, mphamvu ya sensa idzachepetsedwa.Kufunika kwake kumagwirizana kwambiri ndi kuya kwa kufalikira kwa mpweya wina, zomwe zimatengera kukula kwa pore kwa zinthu zomveka.Sakai et al.92 idatengera kukhudzika kwa sensa kuti ikhale ndi mpweya wotulutsa mpweya ndipo idapeza kuti kulemera kwa ma cell a gasi ndi utali wa pore wa nembanemba ya sensa kumakhudza chidwi cha sensa pa kuya kosiyanasiyana kwa mpweya mu nembanemba ya sensor.Zokambirana pamwambapa zikuwonetsa kuti masensa apamwamba a gasi amatha kupangidwa mwa kulinganiza ndikuwongolera magwiridwe antchito a receptor, ntchito ya transducer, ndi zofunikira.
Ntchito yomwe ili pamwambayi ikufotokozera momwe MOS imodzi imagwirira ntchito ndikukambirana zinthu zingapo zomwe zimakhudza momwe MOS imagwirira ntchito.Kuphatikiza pazifukwa izi, masensa a gasi otengera ma heterostructures amatha kupititsa patsogolo magwiridwe antchito popititsa patsogolo ntchito za sensa ndi zolandilira.Kuphatikiza apo, ma heteronanostructures amatha kupititsa patsogolo magwiridwe antchito a sensor popititsa patsogolo machitidwe othandizira, kuwongolera kusamutsa kwa mtengo, ndikupanga masamba ambiri otsatsa.Mpaka pano, masensa ambiri a gasi ozikidwa pa MOS heteronanostructures aphunziridwa kuti akambirane njira zowonjezerera kumva95,96,97.Miller et al.55 inafotokozera mwachidule njira zingapo zomwe zingathe kupititsa patsogolo kukhudzidwa kwa ma heteronanostructures, kuphatikizapo kudalira pamwamba, kudalira mawonekedwe, komanso kudalira.Pakati pawo, mawonekedwe odalira matalikidwe otengera mawonekedwe ndi ovuta kwambiri kuti azitha kugwirizanitsa mawonekedwe onse mu chiphunzitso chimodzi, popeza masensa osiyanasiyana otengera zinthu zopangidwa ndi heteronanostructured (mwachitsanzo, nn-heterojunction, pn-heterojunction, pp-heterojunction, etc.) angagwiritsidwe ntchito. .Schottky mfundo).Nthawi zambiri, masensa opangidwa ndi MOS opangidwa ndi heteronanostructured nthawi zonse amakhala ndi makina awiri kapena kuposerapo98,99,100.Mphamvu ya synergistic ya njira zokulitsa izi zitha kupititsa patsogolo kulandira ndi kukonza ma siginecha a sensor.Chifukwa chake, kumvetsetsa kawonedwe ka masensa otengera zinthu zosasinthika za nanostructured ndikofunikira kuti athandizire ochita kafukufuku kupanga masensa a gasi opita pansi molingana ndi zosowa zawo.Kuphatikiza apo, mawonekedwe a geometric a chipangizocho amathanso kukhudza kwambiri chidwi cha sensor 74, 75, 76. Pofuna kusanthula mwadongosolo kachitidwe ka sensa, njira zodziwikiratu za zida zitatu zochokera kuzinthu zosiyanasiyana za heteronanostructured zidzaperekedwa. ndipo tinakambirana pansipa.
Ndi chitukuko chofulumira cha masensa a gasi a MOS, ma MOS osiyanasiyana a hetero-nanostructured aperekedwa.Kutumiza kwachindunji pa heterointerface kumadalira milingo yosiyanasiyana ya Fermi (Ef) ya zigawozo.Pa heterointerface, ma elekitironi amasuntha kuchokera kumbali imodzi ndi Ef yaikulu kupita kumbali ina ndi Ef yaying'ono mpaka milingo yawo ya Fermi ifika pamlingo, ndi mabowo, mosiyana.Ndiye zonyamulira pa heterointerface zatha ndi kupanga wosanjikiza watha.Sensa ikangokumana ndi mpweya womwe mukufuna, mawonekedwe a heteronanostructured MOS chonyamulira amasintha, monganso kutalika kwa chotchinga, potero kumakulitsa chizindikiro chodziwikiratu.Kuphatikiza apo, njira zosiyanasiyana zopangira ma heteronanostructures zimatsogolera ku ubale wosiyanasiyana pakati pa zida ndi maelekitirodi, zomwe zimatsogolera ku ma geometries a zida ndi njira zosiyanasiyana zowonera.Pakuwunikaku, tikupangira zida zitatu zamtundu wa geometric ndikukambirana momwe zimamvekera pamapangidwe aliwonse.
Ngakhale kuti ma heterojunctions amatenga gawo lofunika kwambiri pakugwira ntchito kwa gasi, geometry ya chipangizo cha sensa yonse imathanso kukhudza kwambiri khalidwe lachidziwitso, popeza malo a sensa conduction channel amadalira kwambiri geometry ya chipangizo.Ma geometries atatu a zida za heterojunction MOS akukambidwa pano, monga momwe zasonyezedwera mu Chithunzi 2. Mu mtundu woyamba, maulumikizidwe awiri a MOS amagawidwa mwachisawawa pakati pa maelekitirodi awiri, ndipo malo a njira yoyendetsera amatsimikiziridwa ndi MOS wamkulu, wachiwiri ndi kupangidwa kwa ma nanostructures osiyanasiyana kuchokera ku MOS yosiyana, pamene MOS imodzi yokha imalumikizidwa ndi electrode.electrode imalumikizidwa, ndiye njira yoyendetsera nthawi zambiri imakhala mkati mwa MOS ndipo imalumikizidwa mwachindunji ndi electrode.Mumtundu wachitatu, zida ziwiri zimalumikizidwa ndi maelekitirodi awiri padera, ndikuwongolera chipangizocho kudzera munjira yolumikizana pakati pa zida ziwirizi.
Kulumikizana pakati pa mankhwala (mwachitsanzo "SnO2-NiO") kumasonyeza kuti zigawo ziwirizi zimangosakanikirana (mtundu I).Chizindikiro cha "@" pakati pa maulumikizidwe awiri (mwachitsanzo, "SnO2@NiO") chimasonyeza kuti scaffold material (NiO) imakongoletsedwa ndi SnO2 pamtundu wa sensa ya mtundu wa II.Kumeta (monga "NiO/SnO2") kumasonyeza mtundu wa kansalu wa III.
Kwa masensa a gasi otengera ma MOS, zinthu ziwiri za MOS zimagawidwa mwachisawawa pakati pa maelekitirodi.Njira zambiri zopangira zida zapangidwa kuti zikonzekeretse zophatikizira za MOS, kuphatikiza sol-gel, coprecipitation, hydrothermal, electrospinning, ndi njira zosakanikirana zamakina98,102,103,104.Posachedwapa, ma metal-organic frameworks (MOFs), kalasi ya zida za porous crystalline zopangidwa ndi zitsulo zopangira zitsulo ndi organic linkers, zakhala zikugwiritsidwa ntchito ngati ma templates popanga ma porous MOS composites105,106,107,108.Ndikoyenera kudziwa kuti ngakhale kuti kuchuluka kwa ma MOS composites ndi ofanana, zizindikiro zokhudzidwa zimatha kusiyana kwambiri pogwiritsa ntchito njira zosiyanasiyana zopangira.109,110 Mwachitsanzo, Gao et al.109 anapanga masensa awiri opangidwa ndi MoO3 ± SnO2 composites ndi ofanana atomiki chiŵerengero. ( Mo: Sn = 1: 1.9 ) ndipo adapeza kuti njira zopangira zosiyana zimatsogolera ku zovuta zosiyanasiyana.Shaposhnik et al.110 inanena kuti machitidwe a co-precipitated SnO2-TiO2 ku gaseous H2 amasiyana ndi zida zosakanikirana zamakina, ngakhale pamlingo womwewo wa Sn/Ti.Kusiyanaku kumachitika chifukwa ubale pakati pa MOP ndi MOP crystallite kukula kumasiyana ndi njira zophatikizira zosiyanasiyana109,110.Pamene kukula kwa tirigu ndi mawonekedwe ake zimagwirizana molingana ndi kachulukidwe ka opereka ndi mtundu wa semiconductor, yankho liyenera kukhala lofanana ngati geometry yolumikizana sisintha 110.Staerz ndi al.111 inanena kuti mawonekedwe a SnO2-Cr2O3 core-sheath (CSN) nanofibers ndi nthaka SnO2-Cr2O3 CSNs anali pafupifupi ofanana, kutanthauza kuti nanofiber morphology sapereka mwayi uliwonse.
Kuphatikiza pa njira zosiyanasiyana zopangira, mitundu ya semiconductor ya ma MOSFET awiri osiyanasiyana imakhudzanso chidwi cha sensa.Itha kugawidwanso m'magulu awiri kutengera ngati ma MOSFET awiriwa ndi amtundu wofanana wa semiconductor (nn kapena pp junction) kapena mitundu yosiyana (pn junction).Pamene magetsi a gasi amachokera kumagulu a MOS amtundu womwewo, posintha chiŵerengero cha molar cha MOS awiriwo, khalidwe la kuyankha lachidziwitso silinasinthe, ndipo mphamvu ya sensa imasiyanasiyana malinga ndi chiwerengero cha nn- kapena pp-heterojunctions.Pamene chigawo chimodzi chimakhala chachikulu mumagulu (mwachitsanzo 0.9 ZnO-0.1 SnO2 kapena 0.1 ZnO-0.9 SnO2), njira yoyendetsera imatsimikiziridwa ndi MOS wamkulu, wotchedwa homojunction conduction channel 92 .Pamene ziwerengero za zigawo ziwirizo zikufanana, zimaganiziridwa kuti njira yoyendetsera galimotoyo imayang'aniridwa ndi heterojunction98,102.Yamazoe et al.112,113 inanena kuti chigawo cha heterocontact cha zigawo ziwirizi chikhoza kusintha kwambiri kukhudzidwa kwa kachipangizo chifukwa chotchinga cha heterojunction chomwe chimapangidwa chifukwa cha ntchito zosiyanasiyana zogwiritsira ntchito zigawozi zimatha kuyendetsa bwino kayendedwe ka sensa yomwe imawululidwa ndi ma electron.Mipweya yosiyanasiyana yozungulira 112,113.Pa mkuyu.Chithunzi 3a ikuwonetsa kuti masensa otengera SnO2-ZnO fibrous hierarchical nyumba okhala ndi zinthu zosiyanasiyana za ZnO (kuyambira 0 mpaka 10 mol% Zn) amatha kuzindikira mosankha.Pakati pawo, kachipangizo zochokera SnO2-ZnO ulusi (7 mol.% Zn) anasonyeza tilinazo kwambiri chifukwa cha mapangidwe ambiri heterojunctions ndi kuwonjezeka m'dera enieni pamwamba, amene anawonjezera ntchito ya Converter ndi bwino. sensitivity 90 Komabe, ndi kuwonjezeka kwina kwa ZnO zomwe zili mu 10 mol.%, gulu la microstructure SnO2-ZnO limatha kukulunga madera otsegulira ndikuchepetsa kukhudzidwa kwa sensa85.Mchitidwe wofananawo umawonedwanso kwa masensa opangidwa ndi NiO-NiFe2O4 pp heterojunction composites ndi Fe / Ni ratios zosiyana (mkuyu 3b)114.
Zithunzi za SEM za ulusi wa SnO2-ZnO (7 mol.% Zn) ndi kuyankha kwa sensa kwa mpweya wosiyanasiyana wokhala ndi 100 ppm pa 260 ° C;54b Mayankho a masensa opangidwa ndi NiO yoyera ndi NiO-NiFe2O4 composites pa 50 ppm ya mpweya wosiyanasiyana, 260 ° C;114 ( c) Chithunzi chojambula cha chiwerengero cha node mu xSnO2-(1-x) Co3O4 kapangidwe ndi kukana kofanana ndi kukhudzidwa kwa xSnO2-(1-x) Co3O4 kapangidwe ka 10 ppm CO, acetone, C6H6 ndi SO2 mpweya pa 350 °C posintha chiŵerengero cha molar cha Sn/Co 98
Zophatikizira za pn-MOS zikuwonetsa machitidwe osiyanasiyana okhudzidwa kutengera chiŵerengero cha atomiki cha MOS115.Kawirikawiri, khalidwe lachidziwitso lamagulu a MOS limadalira kwambiri zomwe MOS imakhala ngati njira yoyamba yoyendetsera sensa.Chifukwa chake, ndikofunikira kwambiri kuwonetsa kuchuluka kwa kapangidwe kake komanso kapangidwe kake ka kompositi.Kim et al.98 adatsimikizira mfundoyi popanga ma xSnO2 ± (1-x) Co3O4 composite nanofibers mwa electrospinning ndi kuphunzira kachipangizo kawo.Iwo adawona kuti khalidwe la SnO2-Co3O4 lopangidwa ndi sensa linasintha kuchokera ku n-mtundu kupita ku p-mtundu mwa kuchepetsa chiwerengero cha SnO2 (mkuyu 3c)98.Kuphatikiza apo, masensa omwe amayendetsedwa ndi heterojunction (ochokera ku 0.5 SnO2-0.5 Co3O4) adawonetsa kuchuluka kwapamtima kwa C6H6 poyerekeza ndi masensa omwe ali ndi homojunction (mwachitsanzo, ma sensor apamwamba a SnO2 kapena Co3O4).Kukana kwakukulu kwachilengedwe kwa 0.5 SnO2-0.5 Co3O4 yochokera ku sensa komanso kuthekera kwake kosinthira kukana kwa sensa yonse kumathandizira kukhudzidwa kwake kwambiri ku C6H6.Kuphatikiza apo, zolakwika za lattice zomwe zimachokera ku SnO2-Co3O4 heterointerfaces zitha kupanga malo otsatsa omwe amakonda ma molekyulu a mpweya, potero kumathandizira kuyankha kwa sensor109,116.
Kuphatikiza pa MOS yamtundu wa semiconductor, kukhudza kwamagulu a MOS kumathanso kusinthidwa pogwiritsa ntchito chemistry ya MOS-117.Huo et al.117 adagwiritsa ntchito njira yosavuta yowotchera kuti akonze zophatikizira za Co3O4-SnO2 ndipo adapeza kuti pamlingo wa Co/Sn molar wa 10%, sensayo idawonetsa kuyankha kwamtundu wa p ku H2 komanso kukhudzika kwamtundu wa n. H2.kuyankha.Mayankho a sensor ku CO, H2S ndi mpweya wa NH3 akuwonetsedwa mu Chithunzi 4a117.Pazigawo zotsika za Co / Sn, ma homojunctions ambiri amapanga malire a SnO2 ± SnO2 nanograin ndikuwonetsa mayankho amtundu wa n-mtundu ku H2 (Figs. 4b, c) 115.Ndi kuwonjezeka kwa chiŵerengero cha Co/Sn mpaka 10 mol.%, mmalo mwa ma homojunctions a SnO2-SnO2, ma heterojunctions ambiri a Co3O4-SnO2 adapangidwa nthawi imodzi (mkuyu 4d).Popeza Co3O4 sichigwira ntchito pokhudzana ndi H2, ndipo SnO2 imakhudzidwa kwambiri ndi H2, momwe H2 imachitira ndi mitundu ya okosijeni ya ionic makamaka imapezeka pamwamba pa SnO2117.Chifukwa chake, ma electron amasunthira ku SnO2 ndi Ef SnO2 amasinthira ku gulu la conduction, pomwe Ef Co3O4 imakhalabe yosasinthika.Chotsatira chake, kukana kwa sensa kumawonjezeka, kusonyeza kuti zipangizo zomwe zili ndi chiwerengero cha Co / Sn chikuwonetsa khalidwe la p-mtundu wa sensing (Mkuyu 4e).Mosiyana ndi zimenezi, mpweya wa CO, H2S, ndi NH3 umachita ndi mitundu ya okosijeni ya ionic pa malo a SnO2 ndi Co3O4, ndipo ma electron amasuntha kuchokera ku gasi kupita ku sensa, zomwe zimapangitsa kuchepa kwa kutalika kwa chotchinga ndi kukhudzidwa kwa mtundu wa n (mkuyu 4f)..Khalidwe losiyanasiyana la sensali ndi chifukwa cha kusinthika kosiyana kwa Co3O4 ndi mpweya wosiyanasiyana, womwe udatsimikiziridwanso ndi Yin et al.118 .Mofananamo, Katoch et al.119 idawonetsa kuti zophatikizira za SnO2-ZnO zili ndi kusankha bwino komanso kukhudzidwa kwakukulu kwa H2.Khalidweli limachitika chifukwa maatomu a H amatha kukopeka mosavuta ku O malo a ZnO chifukwa chakusakanizidwa mwamphamvu pakati pa s-orbital ya H ndi p-orbital ya O, yomwe imatsogolera kuzitsulo za ZnO120,121.
a Co/Sn-10% ma curve osunthika amphamvu ochepetsera mpweya monga H2, CO, NH3 ndi H2S, b, c Co3O4/SnO2 chojambula chojambulira cha H2 chotsika % m.Co/Sn, df Co3O4 Mechanism kuzindikira kwa H2 ndi CO, H2S ndi NH3 yokhala ndi gulu lapamwamba la Co/Sn/SnO2
Chifukwa chake, titha kukulitsa chidwi cha sensa ya mtundu wa I posankha njira zoyenera zopangira, kuchepetsa kukula kwa mbewu zophatikizika, ndikukulitsa chiŵerengero cha molar chamagulu a MOS.Kuphatikiza apo, kumvetsetsa kwakuzama kwa chemistry yazinthu zowoneka bwino kumatha kupititsa patsogolo kusankha kwa sensor.
Mitundu ya sensa ya Type II ndi mawonekedwe ena otchuka a sensa omwe amatha kugwiritsa ntchito mitundu yosiyanasiyana ya nanostructured, kuphatikiza "master" nanomaterial ndi yachiwiri kapena yachitatu nanomaterial.Mwachitsanzo, zinthu zamtundu umodzi kapena ziwiri zokongoletsedwa ndi nanoparticles, core-shell (CS) ndi multilayer heteronanostructured zipangizo zimagwiritsidwa ntchito muzitsulo zamtundu wa II ndipo zidzakambidwa mwatsatanetsatane pansipa.
Pazinthu zoyamba za heteronanostructure (zokongoletsedwa za heteronanostructure), monga momwe tawonetsera mkuyu 2b (1), njira zoyendetsera sensa zimagwirizanitsidwa ndi zinthu zoyambira.Chifukwa cha mapangidwe a heterojunctions, ma nanoparticles osinthidwa angapereke malo okhudzidwa kwambiri a gasi adsorption kapena desorption, ndipo amathanso kukhala othandizira kuti azitha kumva bwino109,122,123,124.Yuan et al.41 adanenanso kuti kukongoletsa ma WO3 nanowires okhala ndi CeO2 nanodots kumatha kupereka malo ambiri otsatsa pa CeO2@WO3 heterointerface ndi CeO2 pamwamba ndikupanga mitundu yambiri ya okosijeni ya chemisorbed kuti igwirizane ndi acetone.Gunawan et al.125. Mphamvu yapamwamba kwambiri ya acetone sensor yochokera ku gawo limodzi la Au@α-Fe2O3 yaperekedwa ndipo yawonedwa kuti kukhudzidwa kwa sensa kumayendetsedwa ndi kuyambitsa kwa mamolekyu a O2 monga gwero la okosijeni.Kukhalapo kwa Au NPs kumatha kukhala ngati chothandizira kulimbikitsa kugawanika kwa mamolekyu a okosijeni kukhala okosijeni wa lattice kwa okosijeni wa acetone.Zotsatira zofananazo zinapezedwa ndi Choi et al.9 pomwe chothandizira cha Pt chidagwiritsidwa ntchito kulekanitsa mamolekyu okosijeni okhala ndi okosijeni wa ionized ndikuthandizira kuyankha kwamphamvu kwa acetone.Mu 2017, gulu lomwelo kafukufuku anasonyeza kuti bimetallic nanoparticles kwambiri imayenera mu catalysis kuposa umodzi wolemekezeka zitsulo nanoparticles, monga momwe chithunzi 5126. 5a ndi schematic wa kupanga ndondomeko platinamu ofotokoza bimetallic (PtM) NPs ntchito apoferritin maselo kukula avareji zosakwana 3 nm.Kenaka, pogwiritsa ntchito njira ya electrospinning, PtM @ WO3 nanofibers anapezedwa kuti awonjezere kukhudzidwa ndi kusankha kwa acetone kapena H2S (Mkuyu 5b-g).Posachedwapa, makina opangira ma atomu amodzi (SACs) awonetsa ntchito yabwino kwambiri yothandizira pothandizira komanso kusanthula gasi chifukwa chakugwiritsa ntchito bwino kwa ma atomu ndi zida zamagetsi zamagetsi127,128.Shin et al.129 inagwiritsa ntchito Pt-SA anchored carbon nitride (MCN), SnCl2 ndi PVP nanosheets monga magwero a mankhwala kukonzekera Pt@MCN@SnO2 ulusi wa inline kuti uzindikire gasi.Ngakhale Pt@MCN imakhala yotsika kwambiri (kuchokera pa 0.13 wt.% mpaka 0.68 wt.%), kudziwika kwa gaseous formaldehyde Pt@MCN@SnO2 ndikopambana zitsanzo zina (pure SnO2, MCN@SnO2 ndi Pt NPs@ SnO2)..Kuchita bwino kwambiri kozindikirika kumeneku kungabwere chifukwa champhamvu kwambiri ya atomiki ya chothandizira cha Pt SA komanso kuphimba kochepa kwa masamba a SnO2129.
Apoferritin-yodzaza encapsulation njira kupeza PtM-apo (PtPd, PtRh, PtNi) nanoparticles;mphamvu yamphamvu ya gasi ya bd pristine WO3, PtPd@WO3, PtRn@WO3, ndi Pt-NiO@WO3 nanofibers;zochokera, mwachitsanzo, pa selectivity katundu wa PtPd@WO3, PtRn@WO3 ndi Pt-NiO@WO3 nanofiber masensa kuti 1 ppm wa kusokoneza gasi 126
Kuphatikiza apo, ma heterojunctions omwe amapangidwa pakati pa zida za scaffold ndi nanoparticles amathanso kusintha njira zoyendetsera bwino pogwiritsa ntchito njira yosinthira ma radial kuti apititse patsogolo sensa130,131,132.Pa mkuyu.Chithunzi 6a chikuwonetsa mawonekedwe a sensa ya SnO2 yoyera ndi Cr2O3@SnO2 nanowires yochepetsera komanso ma oxidizing mpweya ndi njira zofananira za sensor131.Poyerekeza ndi ma nanowires oyera a SnO2, kuyankha kwa Cr2O3@SnO2 nanowires pochepetsa mpweya kumakulitsidwa kwambiri, pomwe kuyankha kwa mpweya wa okosijeni kumakulirakulira.Zochitika izi zimagwirizana kwambiri ndi kutsika kwapamtunda kwa njira zoyendetsera ma SnO2 nanowires mumayendedwe ozungulira a pn heterojunction.Kukaniza kwa sensa kumatha kusinthidwa mwa kusintha kukula kwa EDL pamtunda wa SnO2 nanowires koyera pambuyo pokumana ndi mpweya wochepetsera komanso wowonjezera ma oxidizing.Komabe, kwa Cr2O3 @ SnO2 nanowires, DEL yoyamba ya SnO2 nanowires mumlengalenga imachulukitsidwa poyerekeza ndi ma SnO2 nanowires oyera, ndipo njira yoyendetsera imaponderezedwa chifukwa cha mapangidwe a heterojunction.Choncho, pamene sensa imakhudzidwa ndi mpweya wochepetsera, ma electron otsekedwa amatulutsidwa mu SnO2 nanowires ndipo EDL imachepetsedwa kwambiri, zomwe zimapangitsa kuti zikhale zovuta kwambiri kuposa SnO2 nanowires.Mosiyana ndi izi, posinthira ku mpweya wowonjezera oxidizing, kukulitsa kwa DEL kumakhala kochepa, kumabweretsa kukhudzika kochepa.Choi et al., 133 yomwe SnO2 nanowires yokongoletsedwa ndi p-mtundu wa WO3 nanoparticles imasonyeza bwino kwambiri kuyankha kwapang'onopang'ono kwa mpweya wochepa, pamene n-decorated SnO2 masensa anali ndi chidziwitso cha oxidizing mpweya.TiO2 nanoparticles (Mkuyu 6b) 133. Chotsatira ichi makamaka chifukwa cha ntchito zosiyanasiyana za SnO2 ndi MOS (TiO2 kapena WO3) nanoparticles.Mu p-mtundu (n-mtundu) nanoparticles, njira yoyendetsera zinthu za chimango (SnO2) imakulitsa (kapena mapangano) munjira ya radial, ndiyeno, pochepetsa (kapena oxidation), kukulitsa kwina (kapena kufupikitsa) ya njira yoyendetsera SnO2 - nthiti) ya mpweya (mkuyu 6b).
Makina osinthira ma radial opangidwa ndi LF MOS yosinthidwa.Chidule cha mayankho a gasi ku 10 ppm kuchepetsa ndi oxidizing mpweya kutengera koyera SnO2 ndi Cr2O3 @ SnO2 nanowires ndi lolingana sensing makina schematic zithunzi;ndi njira zofananira za WO3@SnO2 nanorods ndi makina ozindikira133
Mu bilayer ndi multilayer heterostructure zipangizo, conduction njira ya chipangizo cholamulidwa ndi wosanjikiza (kawirikawiri wosanjikiza pansi) pokhudzana mwachindunji ndi maelekitirodi, ndi heterojunction opangidwa pa mawonekedwe a zigawo ziwiri akhoza kulamulira madutsidwe wa wosanjikiza pansi. .Chifukwa chake, mipweya ikalumikizana ndi gawo lapamwamba, imatha kukhudza kwambiri njira zoyendetsera pansi ndi kukana 134 kwa chipangizocho.Mwachitsanzo, Kumar et al.77 idanenanso zotsutsana ndi TiO2@NiO ndi NiO@TiO2 zigawo ziwiri za NH3.Kusiyanaku kumachitika chifukwa njira zoyendetsera masensa awiriwa zimayang'anira zigawo zazinthu zosiyanasiyana (NiO ndi TiO2, motsatana), ndiyeno kusiyanasiyana kwamayendedwe oyambira kumasiyana77.
Bilayer kapena multilayer heteronanostructures amapangidwa kawirikawiri ndi sputtering, atomic layer deposition (ALD) ndi centrifugation56,70,134,135,136.Makulidwe a kanema ndi malo olumikizirana ndi zida ziwirizi zitha kuyendetsedwa bwino.Zithunzi 7a ndi b zikuwonetsa NiO@SnO2 ndi Ga2O3@WO3 nanofilms zopezedwa ndi sputtering kuti zizindikire mowa135,137.Komabe, njirazi nthawi zambiri zimapanga mafilimu athyathyathya, ndipo mafilimu ophwanyikawa sakhudzidwa kwambiri ndi zida za 3D nanostructured chifukwa cha malo awo otsika kwambiri komanso mpweya wodutsa.Choncho, njira yamadzimadzi yopangira mafilimu a bilayer omwe ali ndi maulamuliro osiyanasiyana aperekedwanso kuti apititse patsogolo luso la kulingalira mwa kuwonjezera malo enieni41,52,138.Zhu et al139 kuphatikiza sputtering ndi hydrothermal njira kupanga kwambiri analamula ZnO nanowires pa SnO2 nanowires (ZnO@SnO2 nanowires) kwa H2S kuzindikira (Mkuyu 7c).Yankho lake ku 1 ppm H2S ndilokwera nthawi 1.6 kuposa la sensa yochokera ku ZnO@SnO2 nanofilms.Liu et al.52 inanena kuti kachipangizo kakang'ono ka H2S kameneka kamagwiritsa ntchito njira ziwiri zopangira mankhwala kuti apange mawonekedwe apamwamba a SnO2 @ NiO nanostructures otsatiridwa ndi annealing otentha (mkuyu 10d).Poyerekeza ndi mafilimu odziwika bwino a SnO2 @ NiO bilayer, machitidwe okhudzidwa a SnO2@NiO hierarchical bilayer structure amakhala bwino kwambiri chifukwa chakuwonjezeka kwa malo enieni52,137.
Kachipangizo ka gasi wosanjikiza kawiri kutengera MOS.NiO@SnO2 nanofilm pozindikira ethanol;137b Ga2O3@WO3 nanofilm pozindikira ethanol;135c yolamulidwa kwambiri SnO2@ZnO bilayer hierarchical kapangidwe ka H2S kuzindikira;139d SnO2@NiO bilayer mawonekedwe apamwamba kuti azindikire H2S52.
Pazida zamtundu wa II zozikidwa pa core-shell heteronanostructures (CSHNs), makina ozindikira amakhala ovuta kwambiri, popeza njira zoyendetsera sizimangokhala mu chipolopolo chamkati.Njira zonse zopangira ndi makulidwe (hs) a phukusi amatha kudziwa komwe kuli njira zoyendetsera.Mwachitsanzo, mukamagwiritsa ntchito njira zoyambira pansi-mmwamba, njira zoyendetsera nthawi zambiri zimangokhala pachimake chamkati, chomwe chimakhala chofanana ndi mawonekedwe amitundu iwiri kapena yamitundu yambiri (Mkuyu 2b (3)) 123, 140, 141, 142, 143. Xu et al.144 inanena za njira yapansi-mmwamba yopezera CSHN NiO@α-Fe2O3 ndi CuO@α-Fe2O3 poika wosanjikiza wa NiO kapena CuO NPs pa α-Fe2O3 nanorods momwe njira yoyendetsera inali yochepa ndi gawo lapakati.(nanorods α-Fe2O3).Liu et al.142 idakwanitsanso kuletsa njira yoyendetsera gawo lalikulu la CSHN TiO2 @ Si poyika TiO2 pamapangidwe okonzekera a silicon nanowires.Chifukwa chake, mawonekedwe ake ozindikira (mtundu wa p kapena n-mtundu) amadalira kokha mtundu wa semiconductor wa silicon nanowire.
Komabe, masensa ambiri opangidwa ndi CSHN (mkuyu 2b (4)) adapangidwa ndi kusamutsa ufa wazinthu zopangidwa ndi CS pa tchipisi.Pankhaniyi, njira yoyendetsera sensa imakhudzidwa ndi makulidwe a nyumba (hs).Gulu la Kim lidafufuza momwe hs amagwirira ntchito pozindikira gasi ndipo adaganiza njira yodziwira100,112,145,146,147,148. Zimakhulupirira kuti pali zinthu ziwiri zomwe zimathandizira kuti pakhale njira yodziwikiratu: (1) kusintha kwa radial kwa EDL ya chipolopolo ndi (2) mphamvu yamagetsi yamagetsi (mkuyu 8) 145. Ofufuzawo adanena kuti njira yoyendetsera magetsi za zonyamulira nthawi zambiri zimatsekeredwa ku chipolopolo chosanjikiza pomwe hs> λD ya chipolopolo cha145. Zimakhulupirira kuti pali zinthu ziwiri zomwe zimathandizira kuti pakhale njira yodziwikiratu: (1) kusintha kwa radial kwa EDL ya chipolopolo ndi (2) mphamvu yamagetsi yamagetsi (mkuyu 8) 145. Ofufuzawo adanena kuti njira yoyendetsera magetsi za zonyamulira nthawi zambiri zimatsekeredwa ku chipolopolo chosanjikiza pomwe hs> λD ya chipolopolo cha145. Считается, что в механизме восприятия этой структуры участвуют два фактора: (1) радиальная модуляция ДЭС оболочки и (2) эффект размытия электрического поля (рис. 8) 145. Исследователи отметили, что канал проводимости носителей в основном приурочено к оболочке, когда hs > Chithunzi cha λD145. Zimakhulupirira kuti pali zinthu ziwiri zomwe zimakhudzidwa ndi momwe amaonera kapangidwe kameneka: (1) kusintha kwa radial kwa EDL ya chipolopolo ndi (2) zotsatira za kusokoneza magetsi (mkuyu 8) 145. Ofufuzawo adanena kuti njira yonyamulira imangokhala pachipolopolo pomwe hs> λD zipolopolo145.Zimakhulupirira kuti pali zinthu ziwiri zomwe zimathandizira kuti pakhale njira yodziwira za dongosololi: (1) kusintha kwa radial kwa DEL ya chipolopolo ndi (2) zotsatira za kupaka magetsi (mkuyu 8) 145.研究人员提到传导通道当壳层的hs > λD145 时，载流子的数量主要局限于壳层. > λD145 时，载流子的数量主要局限于壳层. Исследователи отметили, что канал проводимости Когда hs > λD145 оболочки, количество носителей в основном ограничено оболочкой. Ofufuzawo adawona kuti njira yoyendetsera Pamene hs> λD145 ya chipolopolo, chiwerengero cha zonyamulira chimakhala chochepa ndi chipolopolo.Choncho, mu kusinthika kosinthika kwa sensa yochokera ku CSHN, kusintha kwa radial kwa cladding DEL kumapambana (mkuyu 8a).Komabe, pa hs ≤ λD ya chipolopolo, tinthu ta oxygen tomwe timakongoletsedwa ndi chipolopolo ndi heterojunction yomwe imapangidwa pa CS heterojunction imatheratu ma electron. Chifukwa chake, njira yoyendetsera siimangokhala mkati mwa chipolopolo cha chipolopolo komanso pang'ono pakatikati, makamaka pamene hs < λD ya chipolopolo cha chipolopolo. Chifukwa chake, njira yoyendetsera siimangokhala mkati mwa chipolopolo cha chipolopolo komanso pang'ono pakatikati, makamaka pamene hs < λD ya chipolopolo cha chipolopolo. Ndiyeneranso kufotokoza momveka bwino za momwe mungapangire zinthu, komanso kufotokoza momveka bwino <cr. Chifukwa chake, njira yoyendetsera siimakhala mkati mwa chipolopolo chokha, komanso pang'ono pakatikati, makamaka pa hs < λD ya chipolopolo cha chipolopolo.因此，传导通道不仅位于壳层内部，而且部分位于芯部，尤其是当壳层的hs < λD 时. hs < λD 时. Поэтому канал проводимости располагается не только внутри оболочки, но частично pa сердцевине, особенно при hs < λD облочки. Chifukwa chake, njira yoyendetsera sichipezeka mkati mwa chipolopolo, komanso pang'ono pachimake, makamaka pa hs < λD ya chipolopolo.Pankhaniyi, zonse zatha kwathunthu elekitironi chipolopolo ndi pang'ono zatha pachimake wosanjikiza modulate kukana kwa CSHN lonse, chifukwa mu mphamvu kumunda mchira mphamvu (mkuyu. 8b).Kafukufuku wina wagwiritsa ntchito lingaliro la gawo la EDL voliyumu m'malo mwa mchira wamagetsi kuti aunike hs effect100,148.Potengera zopereka ziwirizi, kusinthika kwathunthu kwa kukana kwa CSHN kumafika pamtengo wake waukulu pamene hs ikufanana ndi sheath λD, monga momwe tawonetsera mkuyu 8c.Chifukwa chake, ma hs abwino kwambiri a CSHN amatha kukhala pafupi ndi chipolopolo cha λD, chomwe chimagwirizana ndi zowonera99,144,145,146,149.Kafukufuku wambiri wasonyeza kuti hs ingakhudzenso kukhudzidwa kwa CSHN-based pn-heterojunction sensors40,148.Li et al.148 ndi Bai et al.40 idafufuza mwadongosolo zotsatira za hs pakuchita kwa pn-heterojunction CSHN masensa, monga TiO2@CuO ndi ZnO@NiO, posintha kuzungulira kwa ALD.Zotsatira zake, khalidwe lakumva linasintha kuchoka ku p-mtundu kupita ku n-mtundu ndikuwonjezeka hs40,148.Khalidwe limeneli ndi chifukwa chakuti poyamba (ndi chiwerengero chochepa cha maulendo a ALD) ma heterostructures amatha kuonedwa ngati ma heteronanostructures osinthidwa.Chifukwa chake, njira yoyendetsera imakhala yochepa ndi gawo lapakati (p-type MOSFET), ndipo sensa imawonetsa khalidwe la p-type kuzindikira.Pamene kuchuluka kwa ma ALD akuchulukirachulukira, kusanjikiza kwa cladding (n-type MOSFET) kumakhala kopitilira muyeso ndipo kumakhala ngati njira yoyendetsera, zomwe zimapangitsa chidwi cha mtundu wa n.Khalidwe lofananira lakusintha kwamalingaliro kwanenedwa kwa pn branched heteronanostructures 150,151.Zhou et al.150 idafufuza kukhudzika kwa Zn2SnO4@Mn3O4 nthambi za heteronanostructures powongolera zomwe zili pa Zn2SnO4 pa Mn3O4 nanowires.Pamene nyukiliya ya Zn2SnO4 idapangidwa pamtunda wa Mn3O4, kukhudzidwa kwa mtundu wa p kunawonedwa.Ndi kuwonjezeka kwina kwazomwe zili mu Zn2SnO4, sensa yochokera ku nthambi Zn2SnO4@Mn3O4 heteronanostructures imasinthira ku khalidwe la n-type sensor.
Kufotokozera momveka bwino kwa njira ziwiri zogwirira ntchito za CS nanowires zikuwonetsedwa.Kusintha kwa Resistance modulation chifukwa cha kusintha kwa ma radial kwa zipolopolo zomwe zatha ndi ma elekitironi, b Kuyipa kwa kupaka pakusintha kusinthasintha, ndi c Kusinthasintha kwathunthu kwa CS nanowires chifukwa chophatikiza zonse ziwiri 40
Pomaliza, masensa amtundu wa II amaphatikizanso ma nanostructures osiyanasiyana otsogola, ndipo magwiridwe antchito a sensor amadalira makonzedwe a njira zoyendetsera.Chifukwa chake, ndikofunikira kuyang'anira malo a kanjira ka sensa ndikugwiritsa ntchito mtundu woyenera wa heteronanostructured MOS kuti muphunzire njira yotalikirapo ya masensa amtundu wa II.
Mitundu ya sensa yamtundu wa III siidziwika kwambiri, ndipo njira yoyendetsera imachokera ku heterojunction yomwe imapangidwa pakati pa ma semiconductors awiri olumikizidwa ndi maelekitirodi awiri, motsatana.Mapangidwe apadera a chipangizochi nthawi zambiri amapezeka kudzera muukadaulo wa micromachining ndipo njira zawo zowonera ndizosiyana kwambiri ndi zida ziwiri zam'mbuyomu.Mzere wa IV wa sensa ya Type III nthawi zambiri umakhala ndi mawonekedwe okonzanso chifukwa cha heterojunction mapangidwe48,152,153.Mapiritsi a I-V a heterojunction yabwino amatha kufotokozedwa ndi njira ya thermionic yotulutsa ma elekitironi pamtunda wa chotchinga cha heterojunction152,154,155.
kumene Va ndi voteji kukondera, A ndi chipangizo dera, k ndi Boltzmann mosalekeza, T ndi kutentha mtheradi, q ndi chonyamulira mlandu, Jn ndi Jp ndi dzenje ndi electron kufalikira kachulukidwe panopa, motero.IS imayimira mayendedwe apambuyo, omwe amafotokozedwa kuti: 152,154,155
Choncho, chiwerengero chonse cha pn heterojunction chimadalira kusintha kwa chiwerengero cha onyamula katundu ndi kusintha kwa kutalika kwa chotchinga cha heterojunction, monga momwe zikuwonetsera mu equations (3) ndi (4) 156
pomwe nn0 ndi pp0 ndi kuchuluka kwa ma elekitironi (mabowo) mu mtundu wa n (p-mtundu) MOS, \(V_{bi}^0\) ndi kuthekera komangidwa, Dp (Dn) ndi gawo logawa ma elekitironi (mabowo), Ln (Lp) ndi kutalika kwa ma electron (mabowo), ΔEv (ΔEc) ndi kusintha kwa mphamvu kwa gulu la valence (conduction band) pa heterojunction.Ngakhale kuti kachulukidwe kameneka kakufanana ndi kachulukidwe ka chonyamuliracho, amafanana kwambiri ndi \(V_{bi}^0\).Choncho, kusintha kwakukulu kwa kachulukidwe kamakono kumadalira kwambiri kusinthasintha kwa kutalika kwa chotchinga cha heterojunction.
Monga tafotokozera pamwambapa, kupanga ma MOSFET opangidwa ndi hetero-nanostructured (mwachitsanzo, mtundu wa I ndi mtundu wa II zipangizo) akhoza kusintha kwambiri ntchito ya sensa, m'malo mwa zigawo zapadera.Ndipo pazida zamtundu wa III, mayankho a heteronanostructure akhoza kukhala apamwamba kuposa zigawo ziwiri48,153 kapena apamwamba kuposa chigawo chimodzi76, malingana ndi mankhwala a zinthuzo.Malipoti angapo asonyeza kuti kuyankha kwa heteronanostructures ndipamwamba kwambiri kusiyana ndi gawo limodzi pamene chimodzi mwa zigawozo sichikhudzidwa ndi gas48,75,76,153.Pachifukwa ichi, mpweya womwe umapangidwira udzalumikizana kokha ndi wosanjikiza tcheru ndikupangitsa kusintha kwa Ef kwa chigawo chodziwika bwino ndi kusintha kwa kutalika kwa chotchinga cha heterojunction.Ndiye chiwerengero chonse cha chipangizochi chidzasintha kwambiri, chifukwa chimagwirizana mosagwirizana ndi kutalika kwa chotchinga cha heterojunction malinga ndi equation.(3) ndi (4) 48,76,153.Komabe, pamene zigawo zonse za n-type ndi p-type zimakhudzidwa ndi mpweya womwe mukufuna, ntchito yodziwika ikhoza kukhala pakati.José et al.76 adapanga chithunzithunzi cha porous NiO / SnO2 filimu NO2 mwa sputtering ndipo adapeza kuti chidziwitso cha sensa chinali chapamwamba kuposa cha NiO based sensor, koma chotsika kuposa cha SnO2 based sensor.sensa.Chodabwitsa ichi ndi chifukwa chakuti SnO2 ndi NiO amawonetsa zosiyana ndi NO276.Komanso, chifukwa zigawo ziwirizi zimakhala ndi mphamvu zosiyana za gasi, zikhoza kukhala ndi chizolowezi chofanana chozindikira oxidizing ndi kuchepetsa mpweya.Mwachitsanzo, Kwon et al.157 inapempha NiO / SnO2 pn-heterojunction gas sensor ndi oblique sputtering, monga momwe tawonetsera mkuyu 9a.Chochititsa chidwi n'chakuti, NiO / SnO2 pn-heterojunction sensa inasonyeza zomwe zimakhudzidwa ndi H2 ndi NO2 (mkuyu 9a).Kuti athetse izi, Kwon et al.157 idafufuza mwadongosolo momwe NO2 ndi H2 zimasinthira zonyamulira ndikuwongolera \ (V_{bi}^0\) pazinthu zonse ziwiri pogwiritsa ntchito mawonekedwe a IV ndi zofananira zamakompyuta (mkuyu 9bd).Zithunzi 9b ndi c zikuwonetsa kuthekera kwa H2 ndi NO2 kusintha kuchuluka kwa zonyamulira za masensa kutengera p-NiO (pp0) ndi n-SnO2 (nn0), motsatana.Iwo anasonyeza kuti pp0 wa p-mtundu NiO anasintha pang'ono mu NO2 chilengedwe, pamene izo zinasintha kwambiri mu H2 chilengedwe (mkuyu. 9b).Komabe, kwa n-mtundu wa SnO2, nn0 imachita mosiyana (mkuyu 9c).Malingana ndi zotsatirazi, olembawo adatsimikiza kuti pamene H2 idagwiritsidwa ntchito ku sensa yochokera ku NiO / SnO2 pn heterojunction, kuwonjezeka kwa nn0 kunayambitsa kuwonjezeka kwa Jn, ndipo \ (V_{bi} ^ 0\) kuchepa kwa yankho (mkuyu 9d).Pambuyo pokhudzana ndi NO2, kuchepa kwakukulu kwa nn0 mu SnO2 ndi kuwonjezeka pang'ono kwa pp0 mu NiO kumabweretsa kuchepa kwakukulu kwa \ (V_{bi} ^ 0 \), zomwe zimatsimikizira kuwonjezeka kwa kuyankha kwachidziwitso (mkuyu 9d). ) 157 Pomaliza, kusintha kwa ndende ya zonyamulira ndi \ (V_{bi} ^ 0\) kumabweretsa kusintha kwa chiwerengero chamakono, chomwe chimakhudzanso luso lozindikira.
Makina ozindikira a sensor ya gasi amatengera mawonekedwe a chipangizo cha Type III.Kujambula ma electron microscopy (SEM) zithunzi zodutsa, p-NiO/n-SnO2 chipangizo cha nanocoil ndi mphamvu ya sensor p-NiO/n-SnO2 nanocoil heterojunction sensor pa 200 ° C kwa H2 ndi NO2;b , cross-sectional SEM ya c-chipangizo, ndi zotsatira zofananira za chipangizo chokhala ndi p-NiO b-layer ndi n-SnO2 c-layer.Sensa ya b p-NiO ndi c n-SnO2 sensor muyeso ndikufananiza mawonekedwe a I-V mumpweya wowuma komanso pambuyo powonekera ku H2 ndi NO2.Mapu amitundu iwiri ya kachulukidwe ka b-hole mu p-NiO ndi mapu a c-electrons mu n-SnO2 wosanjikiza ndi sikelo yamtundu adapangidwa pogwiritsa ntchito pulogalamu ya Sentaurus TCAD.d Zotsatira zoyeserera zowonetsa mapu a 3D a p-NiO/n-SnO2 mumpweya wouma, H2 ndi NO2157 m'chilengedwe.
Kuphatikiza pa mankhwala amtundu wa zinthu zomwezo, mawonekedwe a chipangizo chamtundu wa III akuwonetsa kuthekera kopanga makina opangira gasi, zomwe sizingatheke ndi zida za Type I ndi Type II.Chifukwa cha gawo lawo lamagetsi lachilengedwe (BEF), zida za pn heterojunction diode zimagwiritsidwa ntchito popanga zida za Photovoltaic ndikuwonetsa kuthekera kopanga zodzipangira zokha zamagetsi zamagetsi zamagetsi kutentha kutentha pansi pa illulight74,158,159,160,161.BEF pa heterointerface, chifukwa cha kusiyana kwa milingo ya Fermi ya zida, imathandiziranso kupatukana kwa ma electron-hole pairs.Ubwino wa photovoltaic gas sensor yodzipangira yokha ndiyomwe imagwiritsa ntchito mphamvu yochepa chifukwa imatha kuyamwa mphamvu ya kuwala kowunikira ndikudzilamulira yokha kapena zipangizo zina zazing'ono popanda kufunikira kwa gwero lamphamvu lakunja.Mwachitsanzo, Tanuma ndi Sugiyama162 apanga NiO/ZnO pn heterojunctions ngati ma cell a solar kuti ayambitse masensa a SnO2 a polycrystalline CO2.Gad ndi al.74 inanena kuti mphamvu ya photovoltaic gas sensor yokhazikika pa Si / ZnO @ CdS pn heterojunction, monga momwe tawonetsera pa Chithunzi 10a.ZnO nanowires zokhazikika molunjika zidakulitsidwa mwachindunji pamitundu ya p-silicon kuti apange Si/ZnO pn heterojunctions.Kenako ma CdS nanoparticles adasinthidwa pamwamba pa ZnO nanowires ndi kusinthidwa kwa mankhwala.Pa mkuyu.10a ikuwonetsa zotsatira za mayankho a sensa a Si/ZnO@CdS a O2 ndi ethanol.Pansi pa kuunikira, magetsi otseguka (Voc) chifukwa cha kupatukana kwa ma electron-hole awiriawiri pa BEP pa Si / ZnO heterointerface amawonjezeka motsatira ndi chiwerengero cha ma diode ogwirizana74,161.Voc ikhoza kuimiridwa ndi equation.(5) 156,
pomwe ND, NA, ndi Ni ndi kuchuluka kwa opereka, olandila, ndi onyamula mkati, motsatana, ndi k, T, ndi q ndi magawo omwewo monga momwe adakhalira kale.Akakumana ndi mpweya wa oxidizing, amachotsa ma electron kuchokera ku ZnO nanowires, zomwe zimapangitsa kuchepa kwa \(N_D^{ZnO}\) ndi Voc.Mosiyana ndi zimenezi, kuchepetsa mpweya kunachititsa kuwonjezeka kwa Voc (mkuyu 10a).Pamene zokongoletsa ZnO ndi CdS nanoparticles, photoexcited ma elekitironi mu CdS nanoparticles ndi jekeseni mu conduction gulu la ZnO ndi kucheza ndi mpweya adsorbed, potero kuonjezera kuzindikira74,160.Sensa yofanana yodzipangira yokha ya photovoltaic gas yochokera ku Si / ZnO inanenedwa ndi Hoffmann et al.160, 161 (mkuyu 10b).Sensa iyi ikhoza kukonzedwa pogwiritsa ntchito mzere wa amine-functionalized ZnO nanoparticles ([3-(2-aminoethylamino)propyl] trimethoxysilane) (amino-functionalized-SAM) ndi thiol ((3-mercaptopropyl) -functionalized, kusintha ntchito wa gasi chandamale kwa kusankha kusankha NO2 (trimethoxysilane) (thiol-functionalized-SAM)) (Mkuyu 10b) 74,161.
Chojambula chodzipangira chokha cha photoelectric gas chotengera mawonekedwe a chipangizo chamtundu wa III.Self-powered photovoltaic gas sensor based on Si/ZnO@CdS, self-powered sensing mechanism and sensor response to oxidized (O2) ndi kuchepetsa (1000 ppm ethanol) mpweya pansi pa dzuwa;74b Self-powered photovoltaic gas sensor yochokera ku masensa a Si ZnO/ZnO ndi mayankho a sensa kumagasi osiyanasiyana atatha kugwira ntchito kwa ZnO SAM yokhala ndi ma terminal amines ndi thiols 161
Choncho, pokambirana za makina okhudzidwa a masensa amtundu wa III, ndikofunika kudziwa kusintha kwa kutalika kwa chotchinga cha heterojunction ndi mphamvu ya mpweya kuti iwononge ndende yonyamula katundu.Kuphatikiza apo, zowunikira zimatha kupanga zonyamulira zojambulidwa ndi zithunzi zomwe zimachita ndi mpweya, zomwe zimalonjeza kuti zitha kudzipangira okha gasi.
Monga tafotokozera m'mabuku awa, ma heteronanostructures osiyanasiyana a MOS apangidwa kuti apititse patsogolo ntchito ya sensa.Nawonso database ya Webusayiti ya Sayansi idafufuzidwa kuti mupeze mawu osakira osiyanasiyana (zophatikizira zazitsulo zachitsulo, ma oxides achitsulo apakati, ma oxides achitsulo osanjikiza, ndi zowunikira zodzipangira okha) komanso mawonekedwe apadera (kuchuluka, kukhudzika / kusankhidwa, kuthekera kopanga magetsi, kupanga) .Njira Makhalidwe a zipangizo zitatuzi zikuwonetsedwa mu Table 2. Lingaliro lonse la mapangidwe a masensa apamwamba a gasi likukambidwa pofufuza zinthu zitatu zofunika kwambiri zomwe Yamazoe anena.Njira za MOS Heterostructure Sensors Kuti mumvetse zomwe zimayambitsa masensa a gasi, magawo osiyanasiyana a MOS (mwachitsanzo, kukula kwa tirigu, kutentha kwa ntchito, vuto ndi kachulukidwe ka oxygen, ndege zotseguka za crystal) zafufuzidwa mosamala.Kapangidwe kachipangizo, komwe kalinso kofunikira kwambiri pamachitidwe a sensa, sikunyalanyazidwa ndipo sikukambidwanso kawirikawiri.Ndemanga iyi ikukamba za njira zodziwira mitundu itatu ya kachipangizo kachipangizo.
Mapangidwe a kukula kwa mbewu, njira yopangira, ndi kuchuluka kwa ma heterojunctions azinthu zomverera mu sensa ya Type I zitha kukhudza kwambiri chidwi cha sensa.Kuonjezera apo, khalidwe la sensa limakhudzidwanso ndi chiwerengero cha molar cha zigawozo.Mitundu ya zida zamtundu wa II (zokongoletsa za heteronanostructures, bilayer kapena mafilimu ambiri, HSSNs) ndizo zida zodziwika bwino zomwe zimakhala ndi zigawo ziwiri kapena zingapo, ndipo gawo limodzi lokha limalumikizidwa ndi electrode.Pakapangidwe kachipangizochi, kudziwa malo a njira zoyendetsera ndi kusintha kwawo ndikofunikira pakuwunika momwe zimagwirira ntchito.Chifukwa zida zamtundu wa II zikuphatikiza ma hierarchical heteronanostructures osiyanasiyana, njira zambiri zowonera zaperekedwa.Mu mawonekedwe amtundu wa III, njira yoyendetsera imayendetsedwa ndi heterojunction yomwe imapangidwa pa heterojunction, ndipo njira yowonera ndi yosiyana kwambiri.Choncho, ndikofunika kudziwa kusintha kwa kutalika kwa chotchinga cha heterojunction pambuyo powonekera kwa mpweya womwe mukufuna kumtundu wa III.Ndi kapangidwe kameneka, makina opangira magetsi a photovoltaic amatha kupangidwa kuti achepetse kugwiritsa ntchito mphamvu.Komabe, popeza kuti njira yopangira zinthu zaposachedwa ndiyovuta kwambiri ndipo kukhudzika kwake kumakhala kochepa kwambiri kuposa masensa amtundu wa MOS-based chemo-resistive gas, pali kupita patsogolo kwakukulu pakufufuza kwamagetsi odzipangira okha.
Ubwino waukulu wa masensa a MOS a gasi okhala ndi hierarchical heteronanostructures ndi liwiro komanso kukhudzika kwakukulu.Komabe, zovuta zina zazikulu za masensa a gasi a MOS (mwachitsanzo, kutentha kwapamwamba kwa ntchito, kukhazikika kwa nthawi yaitali, kusasankhidwa bwino ndi kubereka, zotsatira za chinyezi, ndi zina zotero) zikadalipo ndipo ziyenera kuthandizidwa zisanayambe kugwiritsidwa ntchito.Masensa amakono a MOS a gasi nthawi zambiri amagwira ntchito kutentha kwambiri ndipo amadya mphamvu zambiri, zomwe zimakhudza kukhazikika kwa nthawi yayitali kwa sensa.Pali njira ziwiri zodziwika bwino zothetsera vutoli: (1) chitukuko cha tchipisi tating'onoting'ono tamphamvu;(2) Kupanga zida zatsopano zomwe zimatha kugwira ntchito kutentha pang'ono kapena ngakhale kutentha.Njira imodzi yopangira tchipisi tating'onoting'onoting'ono ndikuchepetsa kukula kwa sensayo popanga mbale zotenthetsera zotengera za ceramic ndi silicon163.Ma mbale otenthetsera a Ceramic amawononga pafupifupi 50-70 mV pa sensa iliyonse, pomwe mbale zotenthetsera za silicon zokhazikika zimatha kudya pang'ono 2 mW pa sensa iliyonse ikamagwira ntchito mosalekeza pa 300 ° C163,164.Kupanga zida zatsopano zowonera ndi njira yabwino yochepetsera kugwiritsa ntchito mphamvu pochepetsa kutentha kwa ntchito, komanso kumathandizira kukhazikika kwa sensor.Pamene kukula kwa MOS kukupitirirabe kuchepetsedwa kuti awonjezere kukhudzidwa kwa sensa, kukhazikika kwa kutentha kwa MOS kumakhala kovuta kwambiri, komwe kungayambitse kugwedezeka mu chizindikiro cha sensor165.Kuonjezera apo, kutentha kwakukulu kumalimbikitsa kufalikira kwa zipangizo pa heterointerface ndi kupanga magawo osakanikirana, omwe amakhudza mphamvu zamagetsi za sensa.Ofufuzawo akuti kutentha kwabwino kwambiri kwa sensa kumatha kuchepetsedwa posankha zida zoyenera zowonera ndikupanga MOS heteronanostructures.Kufufuza njira yotsika kutentha yopangira ma crystalline MOS heteronanostructures ndi njira ina yodalirika yopititsira patsogolo bata.
Kusankhidwa kwa masensa a MOS ndi nkhani ina yothandiza popeza mipweya yosiyanasiyana imakhala ndi mpweya womwe mukufuna, pomwe masensa a MOS nthawi zambiri amakhudzidwa ndi mpweya wopitilira umodzi ndipo nthawi zambiri amawonetsa chidwi.Chifukwa chake, kukulitsa kusankha kwa sensa ku gasi womwe mukufuna komanso mpweya wina ndikofunikira kuti mugwiritse ntchito.Pazaka makumi angapo zapitazi, chisankhochi chinayankhidwa pang'onopang'ono pomanga makina amagetsi otchedwa "electronic noses (E-nose)" kuphatikizapo ma computational analysis algorithms monga training vector quantization (LVQ), principal component analysis (PCA), etc. e.Mavuto okhudzana ndi kugonana.Partial Least Squares (PLS), etc. 31, 32, 33, 34. Zinthu ziwiri zazikulu (chiwerengero cha masensa, omwe amagwirizana kwambiri ndi mtundu wa zinthu zomverera, ndi kusanthula computational) ndizofunikira kuti pakhale luso la mphuno zamagetsi. kuzindikira mipweya169.Komabe, kuwonjezera kuchuluka kwa masensa nthawi zambiri kumafuna njira zambiri zopangira zovuta, kotero ndikofunikira kupeza njira yosavuta yosinthira magwiridwe antchito a mphuno zamagetsi.Kuphatikiza apo, kusintha MOS ndi zida zina kungapangitsenso kusankha kwa sensor.Mwachitsanzo, kuzindikira kosankhidwa kwa H2 kumatha kutheka chifukwa cha ntchito yabwino yothandizira ya MOS yosinthidwa ndi NP Pd.M'zaka zaposachedwa, ofufuza ena adaphimba MOS MOF pamwamba kuti azitha kusankha bwino pogwiritsa ntchito kukula kwapadera171,172.Mouziridwa ndi ntchitoyi, ntchito zakuthupi zitha kuthetsa vuto la kusankha.Komabe, pali ntchito yambiri yoti ichitidwe posankha zinthu zoyenera.
Kubwereza kwa mawonekedwe a masensa opangidwa pansi pamikhalidwe ndi njira zomwezo ndi chinthu china chofunikira pakupanga kwakukulu komanso kugwiritsa ntchito kothandiza.Nthawi zambiri, centrifugation ndi njira zoviika ndi njira zotsika mtengo zopangira masensa apamwamba a gasi.Komabe, panthawiyi, zinthu zowonongeka zimakonda kuphatikizira ndipo mgwirizano pakati pa zinthu zowonongeka ndi gawo lapansi limakhala lofooka68, 138, 168. Chotsatira chake, kukhudzidwa ndi kukhazikika kwa sensa kumawonongeka kwambiri, ndipo ntchitoyo imakhala yobereka.Njira zina zopangira zinthu monga sputtering, ALD, pulsed laser deposition (PLD), ndi physical vapor deposition (PVD) zimalola kupanga mafilimu a bilayer kapena multilayer MOS mwachindunji pazitsulo za silicon kapena alumina.Njirazi zimapewa kupangika kwa zida zodziwikiratu, kuwonetsetsa kuti sensa imapangidwanso, ndikuwonetsa kuthekera kwa kupanga kwakukulu kwa masensa a planar woonda-filimu.Komabe, kukhudzika kwa mafilimu ophwanyikawa nthawi zambiri kumakhala kotsika kwambiri kuposa kwa 3D nanostructured zipangizo chifukwa cha malo awo ang'onoang'ono apamwamba komanso mpweya wochepa wa mpweya41,174.Njira zatsopano zokulira ma heteronanostructures a MOS m'malo enaake pa ma microarray opangidwa ndikuwongolera bwino kukula, makulidwe, ndi mawonekedwe azinthu zovutirapo ndizofunikira kwambiri pakupanga zotsika mtengo za masensa amtundu wawafer okhala ndi kuberekana kwakukulu komanso kumva.Mwachitsanzo, Liu et al.174 anakonza njira yophatikizira pamwamba ndi pansi yopangira makristali apamwamba kwambiri polima mu situ Ni(OH)2 nanowalls pamalo enaake..Zophika za microburners.
Kuphatikiza apo, ndikofunikiranso kuganizira momwe chinyezi chimakhudzira sensor muzogwiritsa ntchito.Mamolekyu amadzi amatha kupikisana ndi mamolekyu a okosijeni a malo opangira ma sensa ndikukhudza udindo wa sensa pa mpweya womwe umafuna.Monga mpweya, madzi amachita ngati molekyulu kudzera mu kutsekemera kwakuthupi, ndipo amathanso kukhalapo mu mawonekedwe a hydroxyl radicals kapena magulu a hydroxyl pamitundu yosiyanasiyana ya okosijeni kudzera mu chemisorption.Kuonjezera apo, chifukwa cha msinkhu wapamwamba komanso chinyezi chosinthika cha chilengedwe, kuyankha kodalirika kwa sensa ku gasi yomwe ikufuna ndi vuto lalikulu.Njira zingapo zapangidwa kuti zithetse vutoli, monga gasi preconcentration177, chipukuta misozi cha chinyezi ndi njira zowonongeka zowonongeka178, komanso njira zowumitsa179,180.Komabe, njirazi ndizokwera mtengo, zovuta, ndipo zimachepetsa kukhudzidwa kwa sensa.Pali njira zingapo zotsika mtengo zomwe zaperekedwa pofuna kuletsa chinyontho.Mwachitsanzo, kukongoletsa SnO2 ndi Pd nanoparticles akhoza kulimbikitsa kutembenuka kwa adsorbed mpweya mu anionic particles, pamene functionalizing SnO2 ndi zipangizo ndi mkulu kuyanjana kwa mamolekyu madzi, monga NiO ndi CuO, ndi njira ziwiri kuteteza chinyezi kudalira mamolekyu a madzi..Sensor 181, 182, 183. Kuonjezera apo, zotsatira za chinyezi zingathenso kuchepetsedwa pogwiritsa ntchito zipangizo za hydrophobic kupanga hydrophobic surfaces36,138,184,185.Komabe, kupanga makina a gasi osamva chinyezi akadali koyambirira, ndipo njira zotsogola zimafunika kuthana ndi mavutowa.
Pomaliza, kusintha kwa magwiridwe antchito (mwachitsanzo, kukhudzika, kusankha, kutentha kocheperako) kwatheka popanga ma MOS heteronanostructures, ndipo njira zingapo zozindikirira zaperekedwa.Pophunzira makina omvera a sensor inayake, mawonekedwe a geometric a chipangizocho ayeneranso kuganiziridwa.Kufufuza kwa zida zatsopano zowunikira komanso kufufuza njira zopangira zida zapamwamba kudzafunika kuti apititse patsogolo magwiridwe antchito a masensa a gasi ndikuthana ndi zovuta zomwe zatsala m'tsogolomu.Pakuwongolera kowongolera kwa mawonekedwe a sensa, ndikofunikira kupanga mwadongosolo ubale pakati pa njira yopangira zida za sensa ndi ntchito ya heteronanostructures.Kuonjezera apo, kafukufuku wa zochitika zapamtunda ndi kusintha kwa ma heterointerfaces pogwiritsa ntchito njira zamakono zowonetserako zingathandize kufotokozera njira zomwe amazionera ndikupereka malingaliro opangira masensa opangidwa ndi heteronanostructured materials.Pomaliza, kuphunzira kwa njira zamakono zopangira masensa kumatha kulola kupanga ma sensa ang'onoang'ono a gasi pamlingo wawafer pazogwiritsa ntchito mafakitale.
Genzel, NN et al.Kuphunzira kwa nthawi yayitali m'nyumba za nitrogen dioxide ndi zizindikiro za kupuma kwa ana omwe ali ndi mphumu m'matauni.Mdera.Malingaliro aumoyo.116, 1428–1432 (2008).
Nthawi yotumiza: Nov-04-2022
