Ukukhula kwe-SiC silicon carbide single crystal

Ukususela oko yafunyanwa, i-silicon carbide itsale ingqalelo ebanzi. I-Silicon carbide yenziwe zii-athomu ze-Si ezisisiqingatha kunye nee-athomu ze-C ezisisiqingatha, ezidityaniswe zii-covalent bonds ngokusebenzisa ii-electron pairs ezabelana ngee-orbital ze-sp3 hybrid. Kwiyunithi yesakhiwo esisisiseko sekristale yayo enye, ii-athomu ze-Si ezine zicwangciswe kwisakhiwo se-tetrahedral esiqhelekileyo, kwaye i-athomu ye-C ikwimbindi we-tetrahedron eqhelekileyo. Ngokwahlukileyo koko, i-athomu ye-Si inokuthathwa njengembindi we-tetrahedron, ngaloo ndlela yenze i-SiC4 okanye i-CSi4. Isakhiwo se-tetrahedral. I-covalent bond kwi-SiC inamandla kakhulu e-ionic, kwaye amandla e-silicon-carbon bond aphezulu kakhulu, malunga ne-4.47eV. Ngenxa yamandla aphantsi e-stacking fault, iikristale ze-silicon carbide zenza ngokulula ii-polytypes ezahlukeneyo ngexesha lenkqubo yokukhula. Kukho ii-polytypes ezingaphezu kwama-200 ezaziwayo, ezinokwahlulwa zibe ziindidi ezintathu eziphambili: i-cubic, i-hexagonal kunye ne-trigonal.

Okwangoku, iindlela eziphambili zokukhula kweekristale zeSiC ziquka iPhysical Vapor Transport Method (indlela yePVT), iHigh Temperature Chemical Vapor Deposition (indlela yeHTCVD), iLiquid Phase Method, njl. Phakathi kwazo, indlela yePVT ikhulile ngakumbi kwaye ifanelekile ngakumbi kwimveliso yobuninzi kwimizi-mveliso.

Indlela ebizwa ngokuba yi-PVT ibhekisa ekubekeni iikristale zembewu yeSiC phezulu kwe-crucible, kunye nokubeka umgubo weSiC njengezinto eziluhlaza ezantsi kwe-crucible. Kwindawo evaliweyo enobushushu obuphezulu kunye noxinzelelo oluphantsi, umgubo weSiC uyanyibilika kwaye uqhubekele phezulu phantsi kwesenzo somahluko weqondo lobushushu kunye noxinzelelo. Indlela yokuwuthutha uye kufutshane nekristale yembewu uze uyiphinde uyifake kwakhona emva kokufikelela kwimeko eyomileyo. Le ndlela inokufikelela ekukhuleni okulawulekayo kobukhulu bekristale yeSiC kunye neefom ezithile zekristale.
Nangona kunjalo, ukusebenzisa indlela ye-PVT ukukhulisa iikristale zeSiC kufuna ukuba kugcinwe iimeko ezifanelekileyo zokukhula ngexesha lenkqubo yokukhula kwexesha elide, kungenjalo kuya kukhokelela kwingxaki ye-lattice, ngaloo ndlela kuchaphazela umgangatho wekristale. Nangona kunjalo, ukukhula kweekristale zeSiC kugqitywa kwindawo evaliweyo. Zimbalwa iindlela zokujonga ezisebenzayo kunye neendlela ezininzi eziguquguqukayo, ngoko ke ulawulo lwenkqubo lunzima.

Kwinkqubo yokukhulisa iikristale zeSiC ngendlela yePVT, imo yokukhula kwesantya sokuhamba (iStep Flow Growth) ithathwa njengeyona ndlela iphambili yokukhula okuzinzileyo kwefom enye yekristale.
Iiathom zeSi ezivuthulukileyo kunye neeathom zeC ziya kudibana ngokukhethekileyo neeathom zomphezulu wekristale kwindawo yokuqhekeka, apho ziya kwakheka khona kwaye zikhule, nto leyo ebangela ukuba inyathelo ngalinye lihambe phambili ngaxeshanye. Xa ububanzi benyathelo kumphezulu wekristale budlula kakhulu indlela ekhululekileyo yokusasazwa kweeathom, inani elikhulu leeathom linokuhlangana, kwaye indlela yokukhula efana nesiqithi esiphindwe kabini eyenziweyo iya kutshabalalisa indlela yokukhula kokuhamba kwenyathelo, nto leyo ekhokelela ekulahlekelweni kolwazi lwesakhiwo sekristale se-4H, nto leyo ekhokelela kwiimpazamo ezininzi. Ke ngoko, ukulungiswa kweeparameter zenkqubo kufuneka kufezekise ulawulo lwesakhiwo senyathelo lomphezulu, ngaloo ndlela kuthintelwe ukuveliswa kweziphene zepolymorphic, kufezekiswe injongo yokufumana ifom enye yekristale, kwaye ekugqibeleni kulungiselelwe iikristale ezikumgangatho ophezulu.

Njengendlela yokuqala yokukhula kwekristale yeSiC ephuhlisiwe, indlela yokuthutha umphunga obonakalayo yeyona ndlela iphambili yokukhula kwekristale yeSiC. Xa kuthelekiswa nezinye iindlela, le ndlela ineemfuno eziphantsi zezixhobo zokukhula, inkqubo yokukhula elula, ulawulo oluqinileyo, uphando olucokisekileyo lophuhliso, kwaye sele ifikelele kwisicelo semizi-mveliso. Inzuzo yendlela yeHTCVD kukuba inokukhulisa iiwafers eziqhubayo (n, p) kunye ne-high-purity semi-insulating wafers, kwaye inokulawula uxinzelelo lwe-doping ukuze uxinzelelo lwe-carrier kwi-wafer luhlengahlengiswe phakathi kwe-3 × 1013 ~ 5 × 1019 / cm3. Iingxaki ziphezulu umda wobugcisa kunye nesabelo esiphantsi semarike. Njengoko iteknoloji yokukhula kwekristale yeSiC yesigaba solwelo iqhubeka nokuvuthwa, iya kubonisa amandla amakhulu ekuphuculeni lonke ishishini leSiC kwixesha elizayo kwaye inokuba yindawo entsha yokuphumelela ekukhuleni kwekristale yeSiC.