Txij li thaum nws qhov kev tshawb pom, silicon carbide tau nyiam cov neeg nyiam. Silicon carbide yog tsim los ntawm ib nrab Si atoms thiab ib nrab C atoms, uas txuas nrog covalent bonds los ntawm electron khub sib koom sp3 hybrid orbitals. Nyob rau hauv lub hauv paus structural unit ntawm nws ib leeg siv lead ua, plaub Si atoms yog teem nyob rau hauv ib tug li niaj zaus tetrahedral qauv, thiab C atom nyob rau hauv nruab nrab ntawm lub tetrahedron li niaj zaus. Hloov pauv, Si atom tseem tuaj yeem suav tias yog qhov chaw nruab nrab ntawm tetrahedron, yog li tsim SiC4 lossis CSi4. Tetrahedral qauv. Covalent daim ntawv cog lus nyob rau hauv SiC yog heev ionic, thiab silicon-carbon bond zog yog siab heev, txog 4.47eV. Vim yog lub zog qis qis qis, silicon carbide crystals yooj yim tsim ntau yam polytypes thaum txoj kev loj hlob. Muaj ntau tshaj 200 paub polytypes, uas tuaj yeem muab faib ua peb pawg loj: cubic, hexagonal thiab trigonal.
Tam sim no, txoj kev loj hlob tseem ceeb ntawm SiC crystals muaj xws li Lub Cev Vapor Transport Method (PVT method), Kub Kub Chemical Vapor Deposition (HTCVD method), Liquid Phase Method, thiab lwm yam. ntau lawm. cov
Txoj kev hu ua PVT yog hais txog kev tso SiC cov noob muaju rau saum lub crucible, thiab muab SiC hmoov ua raw khoom rau hauv qab ntawm lub crucible. Nyob rau hauv qhov chaw kaw ntawm qhov kub thiab txias tsis tshua muaj siab, SiC hmoov sublimates thiab txav mus rau hauv qhov kev txiav txim ntawm qhov kub thiab txias gradient thiab concentration sib txawv. Ib txoj hauv kev thauj nws mus rau thaj tsam ntawm cov noob siv lead ua thiab tom qab ntawd recrystallizing nws tom qab ncav cuag lub xeev supersaturated. Txoj kev no tuaj yeem ua tiav kev loj hlob ntawm SiC siv lead ua loj thiab cov ntaub ntawv siv lead ua tshwj xeeb. cov
Txawm li cas los xij, kev siv PVT txoj kev loj hlob SiC crystals yuav tsum tau ua kom muaj kev loj hlob tsim nyog thaum lub sij hawm txoj kev loj hlob mus ntev, txwv tsis pub nws yuav ua rau lattice teeb meem, yog li cuam tshuam rau qhov zoo ntawm cov siv lead ua. Txawm li cas los xij, kev loj hlob ntawm SiC crystals tiav hauv qhov chaw kaw. Muaj ob peb txoj kev saib xyuas zoo thiab ntau qhov sib txawv, yog li kev tswj cov txheej txheem nyuaj.
Nyob rau hauv tus txheej txheem ntawm kev loj hlob SiC crystals los ntawm txoj kev PVT, cov kauj ruam khiav txoj kev loj hlob (Step Flow Growth) yog suav hais tias yog lub ntsiab mechanism rau kev loj hlob ruaj khov ntawm ib daim ntawv siv lead ua.
Cov vaporized Si atoms thiab C atoms yuav nyiam sib txuas nrog crystal deg atoms ntawm lub kink point, qhov chaw uas lawv yuav nucleate thiab loj hlob, ua rau txhua kauj ruam ntws mus rau hauv tib lub sijhawm. Thaum cov kauj ruam dav ntawm lub ntsej muag siv lead ua nyob deb tshaj qhov diffusion dawb txoj kev ntawm adatoms, ib tug loj tus naj npawb ntawm adatoms tej zaum yuav agglomerate, thiab ob-dimensional kob-zoo li txoj kev loj hlob hom tsim yuav rhuav tshem cov kauj ruam khiav txoj kev loj hlob, ua rau poob ntawm 4H. Crystal qauv ntaub ntawv, ua rau ntau yam tsis xws luag. Yog li ntawd, kev hloov pauv ntawm cov txheej txheem yuav tsum ua tiav cov kev tswj ntawm cov txheej txheem saum npoo av, yog li inhibiting tiam ntawm polymorphic tsis xws luag, ua tiav lub hom phiaj ntawm kev tau txais ib daim ntawv siv lead ua, thiab thaum kawg npaj cov khoom siv lead ua zoo.
Raws li qhov ntxov tshaj plaws tsim SiC siv lead ua txoj kev loj hlob, lub cev vapor thauj txoj kev yog tam sim no txoj kev loj hlob tseem ceeb tshaj plaws rau kev loj hlob SiC crystals. Piv nrog rau lwm txoj kev, txoj kev no muaj qis dua rau cov cuab yeej loj hlob, cov txheej txheem kev loj hlob yooj yim, muaj zog tswj, kev tshawb fawb txog kev loj hlob, thiab tau ua tiav daim ntawv thov kev lag luam. Qhov zoo ntawm HTCVD txoj kev yog tias nws tuaj yeem loj hlob conductive (n, p) thiab high-purity semi-insulating wafers, thiab tuaj yeem tswj cov doping concentration kom cov cab kuj concentration hauv wafer yog adjustable ntawm 3 × 1013 ~ 5 × 1019. /cm3. Qhov tsis zoo yog qhov chaw ua haujlwm siab thiab kev lag luam qis. Raws li cov kua-theem SiC siv lead ua kev loj hlob thev naus laus zis txuas ntxiv mus rau kev paub tab, nws yuav qhia tau tias muaj peev xwm ua tau zoo rau kev ua tiav tag nrho SiC kev lag luam yav tom ntej thiab zoo li yuav yog qhov tshiab ntawm SiC siv lead ua kev loj hlob.
Post lub sij hawm: Apr-16-2024