Txij li thaum nws nrhiav tau, silicon carbide tau nyiam kev saib xyuas dav dav. Silicon carbide yog tsim los ntawm ib nrab Si atoms thiab ib nrab C atoms, uas txuas nrog los ntawm covalent bonds los ntawm electron khub sib koom sp3 hybrid orbitals. Hauv chav tsev qauv yooj yim ntawm nws cov siv lead ua ib leeg, plaub Si atoms tau teeb tsa hauv cov qauv tetrahedral ib txwm muaj, thiab C atom nyob hauv nruab nrab ntawm tetrahedron ib txwm muaj. Ntawm qhov tod tes, Si atom kuj tuaj yeem suav tias yog qhov chaw ntawm tetrahedron, yog li tsim SiC4 lossis CSi4. Tetrahedral qauv. Cov ntawv cog lus covalent hauv SiC yog ionic heev, thiab lub zog sib koom ua ke silicon-carbon siab heev, txog 4.47 eV. Vim yog lub zog qis stacking fault, silicon carbide crystals yooj yim tsim ntau yam polytypes thaum lub sijhawm loj hlob. Muaj ntau dua 200 polytypes paub, uas tuaj yeem faib ua peb pawg loj: cubic, hexagonal thiab trigonal.
Tam sim no, cov txheej txheem loj hlob tseem ceeb ntawm SiC crystals suav nrog Physical Vapor Transport Method (PVT method), High Temperature Chemical Vapor Deposition (HTCVD method), Liquid Phase Method, thiab lwm yam. Ntawm lawv, PVT method yog qhov paub tab dua thiab tsim nyog dua rau kev tsim khoom loj hauv kev lag luam.
Txoj kev hu ua PVT txhais tau hais tias muab cov noob SiC siv lead ua ke rau saum lub crucible, thiab muab cov hmoov SiC ua cov khoom siv raw rau hauv qab ntawm lub crucible. Hauv qhov chaw kaw uas muaj qhov kub thiab txias thiab qhov siab qis, cov hmoov SiC yuav sublimate thiab txav mus rau sab saud raws li qhov kub thiab txias thiab qhov sib txawv ntawm qhov concentration. Ib txoj kev thauj nws mus rau thaj tsam ntawm cov noob siv lead ua ke thiab tom qab ntawd rov ua dua tom qab mus txog lub xeev supersaturated. Txoj kev no tuaj yeem ua tiav kev loj hlob ntawm SiC siv lead ua ke thiab cov qauv siv lead ua ke.
Txawm li cas los xij, siv txoj kev PVT los cog cov SiC crystals yuav tsum tau tswj hwm cov xwm txheej kev loj hlob kom zoo thaum lub sijhawm ntev, txwv tsis pub nws yuav ua rau muaj kev tsis sib haum xeeb, yog li cuam tshuam rau qhov zoo ntawm cov crystal. Txawm li cas los xij, kev loj hlob ntawm SiC crystals tau ua tiav hauv qhov chaw kaw. Muaj ob peb txoj kev saib xyuas zoo thiab ntau yam hloov pauv, yog li kev tswj hwm cov txheej txheem nyuaj.
Hauv cov txheej txheem ntawm kev loj hlob SiC siv lead ua los ntawm txoj kev PVT, hom kev loj hlob ntawm cov kauj ruam (Kauj Ruam Kev Loj Hlob) yog suav tias yog lub hauv paus tseem ceeb rau kev loj hlob ruaj khov ntawm ib daim ntawv siv lead ua.
Cov atoms Si uas tau ua pa thiab C atoms yuav nyiam sib txuas nrog cov atoms ntawm qhov chaw siv lead ua ke ntawm qhov chaw kink, qhov chaw uas lawv yuav nucleate thiab loj hlob, ua rau txhua kauj ruam ntws mus rau pem hauv ntej. Thaum qhov dav ntawm qhov chaw siv lead ua ke ntau dua li txoj kev sib kis ntawm adatoms, ntau tus adatoms yuav sib sau ua ke, thiab hom kev loj hlob zoo li kob ob-seem uas tsim los yuav rhuav tshem hom kev loj hlob ntawm cov kauj ruam, ua rau poob ntawm cov ntaub ntawv qauv siv lead ua ke 4H, ua rau muaj ntau qhov tsis zoo. Yog li ntawd, kev hloov kho ntawm cov txheej txheem yuav tsum ua tiav kev tswj hwm ntawm cov qauv kauj ruam ntawm qhov chaw, yog li ntawd txwv tsis pub tsim cov teeb meem polymorphic, ua tiav lub hom phiaj ntawm kev tau txais ib daim ntawv siv lead ua ke, thiab thaum kawg npaj cov siv lead ua ke zoo.
Raws li txoj kev loj hlob ntawm SiC siv lead ua thaum ub, txoj kev thauj mus los ntawm lub cev yog txoj kev loj hlob tseem ceeb tshaj plaws rau kev loj hlob ntawm SiC siv lead ua. Piv nrog rau lwm txoj kev, txoj kev no muaj qhov yuav tsum tau siv cov khoom siv loj hlob tsawg dua, cov txheej txheem loj hlob yooj yim, kev tswj hwm muaj zog, kev tshawb fawb txog kev loj hlob zoo, thiab twb tau ua tiav kev siv hauv kev lag luam lawm. Qhov zoo ntawm txoj kev HTCVD yog tias nws tuaj yeem loj hlob cov wafers conductive (n, p) thiab cov wafers semi-insulating uas muaj purity siab, thiab tuaj yeem tswj tau qhov concentration doping kom qhov concentration ntawm cov carrier hauv wafer tuaj yeem hloov kho tau ntawm 3 × 1013 ~ 5 × 1019 / cm3. Qhov tsis zoo yog qhov kev txwv kev siv tshuab siab thiab feem lag luam qis. Raws li cov thev naus laus zis loj hlob ntawm SiC siv lead ua kua txuas ntxiv mus, nws yuav qhia txog lub peev xwm zoo hauv kev txhim kho tag nrho kev lag luam SiC yav tom ntej thiab yuav yog qhov tshiab hauv kev loj hlob ntawm SiC siv lead ua.
Lub sijhawm tshaj tawm: Plaub Hlis-16-2024