Xim Txheej Txheem Txheej Txheem Ntawm Semiconductors Thiab Insulators

Xim tiam tshuab ntawm semiconductors thiab insulators

Qhov tseem ceeb sib txawv ntawm cov coj thiab semiconductors thiab cov rwb thaiv tsev yog qhov tsis muaj qhov sib txawv ntawm pawg. Nyob rau hauv tus neeg xyuas pib, lub valence band thiab cov kab ke ua ke nrog sib tshooj. Tsis muaj qhov sib txawv nruab nrab ntawm lawv. Hluav taws xob txav tau yooj yim. Txawm li cas los xij, hauv semiconductors thiab cov kab hluav taws xob, muaj qhov sib txawv nruab nrab ntawm lawv cov valence band thiab band band. Qhov sib txawv ntawm qhov sib txawv ntawm cov khoom sib txawv yog txawv, thiab qhov sib txawv dav ntawm cov rwb thaiv tsev yog ntau dav dua qhov ntawm semiconductors. Hauv lub tshuab hluav taws xob semiconductor, valence band electrons nqus tau lub zog txaus kom yooj yim lub zog mus rau cov twj paj nruag conduction. Hauv qhov hluav taws xob tiv thaiv, valence band electrons tsis tuaj yeem tau txais lub zog dhau qhov qhov dav dav ntawm qhov tsis muaj peev xwm los ntawm thermal excitation thiab dhia mus rau kev sib dhos. Yog li ntawd, muaj ob peb lub tshuab hluav taws xob nyob hauv qhov sib txig ntawm pawg ntawm cov rwb thaiv tsev, yog li yuav luag tsis muaj kev sib txuam.

Semiconductors thiab cov rwb thaiv tsev pom nyob rau hauv cov xwm feem ntau suav nrog ceramics thiab polymers, uas muaj cov kab khoob. Qhov ntev ntawm qhov pom ntawm lub teeb yog 380-760nm, thiab lub photon lub zog ntawm lub zog tshaj plaws violet lub teeb yog txog 3.2ev. Thaum cov kab sib txawv ntawm cov rwb thaiv tsev tsis txaus siab dhau 3.2eV, lub rwb thaiv tsev yuav tsis nqus ib qho pom kev, uas tuaj yeem xa mus kom tiav.Raws li cov ntsiab lus no, cov xim ntawm cov rwb thaiv tsev yuav cuam tshuam los ntawm nws cov microstructure. Piv txwv, monocrystalline alumina yog pob tshab; Polycrystalline alumina, vim yog qhov sib txawv refractive ntawm cov nplej sib txawv, ua rau qhov teeb meem tawg lub teeb nyob rau hauv cov txheej txheem ntawm kev tawm sab hauv ntawm cov siv lead ua, uas txo qhov pom ntawm cov khoom siv; Polycrystalline lossis ntxeem tau alumina yog tsis pom meej vim qhov tawg ntawm qhov teeb meem ntau dua. Cov khoom siv yog xim dawb.

Raug cov ionic tebchaw tsuas tuaj yeem nqus tau lub teeb nyob hauv cheeb tsam ultraviolet muaj qhov tso siab ntau dua, tab sis tsis yog lub teeb nyob hauv thaj av optic. Yog li no, cov roj ntsha ionic cov sib txuas feem ntau tsis muaj kob lossis dawb paug. Thaum cov hlau cation thiab anion ntawm cov compound sib txuas nrog sib, cov hluav taws xob hluav taws xob huab sib tshooj rau qee qhov thiab qhia tau tseeb qee yam covalency. Thaum covalency ntawm lub compound mus txog qib siab, nws nqus ib feem ntawm lub teeb xim, ua rau lub chaw tshwm muaj qee xim. Nrog rau qhov nce ntawm covalency ntawm lub compound, qhov nqus ntawm cov pom lub teeb ntxiv, thiab xim ntawm cov sib txuas maj mam sib zog. Nws covalency nyob ntawm lub polarization thiab deformability ntawm hlau cations thiab anions. Yog hais tias lub polarization thiab deformation ntawm ions yog qhov loj, lub compound muaj cov muaj zog thiab cov xim tsaus nti.

Feem ntau, cov hluav taws xob tsis tsim muaj feem ntau yuav nqus tau lub zog thiab dhia dua li cov hluav taws xob ua ke, yog li cov ntaub ntawv feem ntau peb ntsib muaj cov hluav taws xob tsis xws, xws li Fe3 +, Cu2 +, thiab Peb tau pom tias kev hloov hlau ions muaj xim nplua nuj vim tias lawv tau ntsib ob qho tib si ntawm cov xwm txheej saum toj no:

(1) muaj cov hluav taws xob tsis zoo;

(2) Lub zog sib txawv ntawm cov orbitals tom qab sib cais ntawm hluav taws xob orbital theem qib poob hauv qhov ntau ntawm qhov pom ntawm lub zog.

Cov kev hloov pauv hloov hlau ions feem ntau muaj nyob rau hauv daim ntawv ntawm txoj hauv kev, xws li hydrates, ammonia complexes, cyanide complexes, thiab lwm yam. Lawv feem ntau nrog kev sib cais ntawm d orbital zog theem hauv cov txheej txheem ntawm txoj kev ua ntau, uas cuam tshuam txog kev teeb tsa ntawm nyuaj thiab cov khoom ntawm ligands lawv tus kheej. Lub tshuab hluav taws xob thaum xub thawj tau tsib lub zog sib luag: dxyj dyz DZX dx2-y2 dz2. Thawj peb ntawm lawv yog nyob rau ntawm Kaum Kaum 45 degrees nrog txoj kab sib chaws. Dx2-y2 nyob rau ntawm lub dav hlau xy thiab nyob rau hauv tib qho kev coj ua nrog txoj kab sib tshuam. Dz2 yog dumbbell zoo li tus ntiv nplhaib thiab txuas ntxiv raws li z axis.

Cov tsib hom ntawm orbitals cuam tshuam thiab txwv los ntawm ligands mus rau qib sib txawv hauv cov txheej txheem ntawm kev tsim cov ceg. Piv txwv li, xav txog octahedral ua kom sib haum teeb tsa hydrate nrog tus txheej txheem kev sib koom tes ntawm 6, vim tias ligand tsuas yog nyob hauv peb txoj kab kev taw qhia ntawm lub nruab nrab nruab nrab ion, uas yog, muaj kev sib ceg nrog cov kev taw qhia txuas ntxiv ntawm dx2-y2dz2, tom qab ntawd ob d orbitals ntawm nruab nrab ion raug tso tawm los ntawm qhov tsis zoo ntawm lub ligand thiab lub zog nce ntau dua.Qhov lwm peb d orbitals stagger nrog ligand, thiab lub zog hloov tau me dua li ntawm dx2-y2dz2. Lub caj qaum d ntawm lub zog nruab nrab ntawm cov nruab nrab ion tau faib ua ob pawg: cov sib zog sib zog ntawm cov zog dx2-y2dz2 thiab lub zog hluav taws xob tsis tshua muaj zog dz dyz DZX, uas lub zog sib txawv (nruab nrab ntawm 1.99 · 10-19j thiab 5.96 · 10-19j) muaj qee yam poob tsis pub dhau lub teeb pom kev zoo (5.5 · 10-19 thiab 3.0 · 10-19). D xaim hluav taws xob yooj yim dhia ntawm ob txheej ntawm lub teb, tsim cov xim ntawm lub teeb uas tib neeg lub qhov muag pom tau.

Organic polymer cov ntaub ntawv, txawm li cas los xij, feem ntau yog ib chav kawm ntawm cov sib txuas uas yog covalent daim ntawv cog lus. Saturated organic molecules sau nkaus nkaus ntawm cov pob txha sib txuas tau zoo heev hauv cov qauv thiab yuav tsum muaj lub zog siab dua kom muaj siab cov hluav taws xob. Yog li no, lub teeb nqus hluav taws xob nyob hauv thaj tsam deb dhau ultraviolet muaj ntau qhov ntau dua, uas txiav txim siab tias cov organic sib txuas ua ke los ntawm kev sib khi yog cov xim tsis muaj xim.

2.3 qhov xim xim ntawm cov blocks thiab hmoov
Hauv ntej, qhov tseem ceeb ntawm cov xim ntawm cov teeb meem, txawm tias tus neeg xyuas pib, semiconductor lossis insulator, yog qhov kev xaiv nqus ntawm lub teeb pom.

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