Lub hauv paus ntsiab lus ntawm LED

Tag nrholub teeb ua haujlwm uas rov ua dua tshiab tau, lub teeb pom kev zoo nqa tauthiablub teeb taub hau ntau yamsiv hom teeb LED. Yuav kom nkag siab txog lub hauv paus ntsiab lus ntawm diode coj, ua ntej nkag siab txog kev paub yooj yim ntawm semiconductors. Cov khoom siv hluav taws xob ntawm cov khoom siv semiconductor yog nyob nruab nrab ntawm cov conductors thiab insulators. Nws cov yam ntxwv tshwj xeeb yog: thaum lub semiconductor raug txhawb los ntawm lub teeb sab nraud thiab cov cua sov, nws lub peev xwm conductive yuav hloov pauv ntau; Ntxiv me me ntawm cov khoom tsis huv rau lub semiconductor ntshiab ua rau nws muaj peev xwm ua hluav taws xob ntau ntxiv. Silicon (Si) thiab germanium (Ge) yog cov semiconductors siv ntau tshaj plaws hauv cov khoom siv hluav taws xob niaj hnub no, thiab lawv cov electrons sab nraud yog plaub. Thaum silicon lossis germanium atoms tsim ib lub siv lead ua, cov atoms nyob sib ze sib cuam tshuam nrog ib leeg, yog li ntawd cov electrons sab nraud tau sib koom los ntawm ob lub atoms, uas tsim cov qauv sib koom ua ke hauv lub siv lead ua, uas yog cov qauv molecular nrog me ntsis kev txwv tsis pub muaj peev xwm. Ntawm chav tsev kub (300K), thermal excitation yuav ua rau qee cov electrons sab nraud tau txais lub zog txaus los tawg ntawm cov ntawv cog lus covalent thiab dhau los ua cov electrons dawb, cov txheej txheem no hu ua intrinsic excitation. Tom qab lub electron tsis khi los ua ib lub electron dawb, qhov chaw seem tshuav hauv cov ntawv cog lus covalent. Qhov chaw seem no hu ua qhov. Qhov tsos ntawm lub qhov yog ib qho tseem ceeb uas ua rau lub semiconductor txawv ntawm tus neeg xyuas pib.

Thaum ntxiv me ntsis pentavalent impurity xws li phosphorus rau hauv intrinsic semiconductor, nws yuav muaj ib qho electron ntxiv tom qab tsim covalent bond nrog lwm cov semiconductor atoms. Qhov electron ntxiv no tsuas yog xav tau lub zog me me kom tshem tawm cov bond thiab ua ib qho free electron. Hom impurity semiconductor no hu ua electronic semiconductor (N-type semiconductor). Txawm li cas los xij, ntxiv me ntsis trivalent elemental impurities (xws li boron, thiab lwm yam) rau intrinsic semiconductor, vim nws tsuas muaj peb lub electrons hauv txheej sab nraud, tom qab tsim covalent bond nrog cov semiconductor atoms nyob ib puag ncig, nws yuav tsim ib qho chaw seem hauv lub crystal. Hom impurity semiconductor no hu ua hole semiconductor (P-type semiconductor). Thaum N-type thiab P-type semiconductors sib koom ua ke, muaj qhov sib txawv ntawm qhov concentration ntawm cov free electrons thiab qhov ntawm lawv qhov sib tshuam. Ob qho electrons thiab qhov tau diffused mus rau qhov concentration qis dua, tawm hauv qab them tab sis immobile ions uas rhuav tshem qhov qub hluav taws xob neutrality ntawm N-type thiab P-type cheeb tsam. Cov khoom me me uas tsis txav tau no feem ntau hu ua cov nqi chaw, thiab lawv tau sib sau ua ke ze ntawm qhov sib tshuam ntawm thaj tsam N thiab P los tsim ib thaj tsam nyias nyias ntawm cov nqi chaw, uas hu ua PN sib tshuam.

Thaum lub zog hluav taws xob pem hauv ntej raug siv rau ob qho kawg ntawm PN qhov sib tshuam (lub zog hluav taws xob zoo rau ib sab ntawm P-hom), cov qhov thiab cov electrons dawb txav mus los ib puag ncig, tsim kom muaj lub zog hluav taws xob sab hauv. Cov qhov tshiab txhaj tshuaj tom qab ntawd rov ua ke nrog cov electrons dawb, qee zaum tso tawm lub zog ntau dhau hauv daim ntawv ntawm photons, uas yog lub teeb uas peb pom los ntawm leds. Cov spectrum zoo li no yog qhov nqaim heev, thiab vim tias txhua yam khoom muaj qhov sib txawv ntawm band, qhov wavelengths ntawm photons tso tawm yog txawv, yog li cov xim ntawm leds yog txiav txim siab los ntawm cov khoom siv yooj yim siv.