Lub hauv paus txheej txheem ntawmSiCsiv lead ua kev loj hlob yog muab faib ua sublimation thiab decomposition ntawm raw cov ntaub ntawv nyob rau hauv high kub, kev thauj mus los ntawm cov roj theem tshuaj nyob rau hauv qhov kev txiav txim ntawm kub gradient, thiab recrystallization loj hlob ntawm cov roj theem ntawm cov noob siv lead ua. Raws li qhov no, sab hauv ntawm lub crucible yog muab faib ua peb ntu: raw khoom cheeb tsam, loj hlob chamber thiab noob siv lead ua. Ib tug lej simulation qauv tau kos raws li qhov tseeb resistiveSiCib leeg siv lead ua loj hlob (saib daim duab 1). Hauv kev suav: hauv qab ntawm lubcrucibleyog 90 hli nyob rau hauv qab ntawm lub rhaub, qhov kub ntawm lub crucible yog 2100 ℃, raw khoom particle inch yog 1000 μm, lub porosity yog 0.6, kev loj hlob siab yog 300 Pa, thiab lub sij hawm loj hlob yog 100 h. . Lub PG thickness yog 5 hli, txoj kab uas hla yog sib npaug rau sab hauv txoj kab uas hla ntawm lub crucible, thiab nws nyob 30 hli saum cov khoom siv raw. Cov txheej txheem sublimation, carbonization, thiab recrystallization ntawm cov khoom siv raw khoom raug txiav txim siab hauv kev suav, thiab cov tshuaj tiv thaiv ntawm PG thiab roj theem tsis raug txiav txim siab. Cov cuab yeej suav nrog lub cev muaj feem cuam tshuam yog qhia hauv Table 1.
Daim duab 1 Simulation xam cov qauv. (a) Thermal teb qauv rau siv lead ua kev loj hlob simulation; (b) Kev faib cov cheeb tsam sab hauv ntawm lub crucible thiab cov teeb meem ntawm lub cev
Table 1 Qee qhov ntsuas lub cev siv hauv kev suav
Daim duab 2(a) qhia tau hais tias qhov kub ntawm PG-muaj cov qauv (cim raws li qauv 1) yog siab tshaj ntawm cov qauv PG-dawb (tus qauv 0) hauv qab PG, thiab qis dua cov qauv 0 saum PG. Lub zuag qhia tag nrho qhov kub thiab txias gradient nce, thiab PG ua raws li cov cua sov-insulating tus neeg sawv cev. Raws li cov duab 2(b) thiab 2(c), axial thiab radial kub gradients ntawm cov qauv 1 nyob rau hauv cov khoom siv raw khoom yog me me, qhov kub thiab txias faib yog ntau yam, thiab sublimation ntawm cov khoom yog ntau tiav. Tsis zoo li cov khoom siv raw khoom, Daim duab 2(c) qhia tau hais tias cov radial kub gradient ntawm cov noob siv lead ua ntawm cov qauv 1 yog loj dua, uas tej zaum yuav tshwm sim los ntawm cov proportions sib txawv ntawm txawv tshav kub hloov hom, uas yuav pab cov siv lead ua loj hlob nrog ib tug convex interface. . Nyob rau hauv daim duab 2(d), qhov kub ntawm qhov chaw sib txawv nyob rau hauv lub crucible qhia tau hais tias ib tug zuj zus sib txawv raws li kev loj hlob, tab sis qhov kub ntawm qhov sib txawv ntawm cov qauv 0 thiab cov qauv 1 maj mam txo nyob rau hauv lub raw khoom cheeb tsam thiab maj mam nce nyob rau hauv lub loj hlob chamber.
Daim duab 2 Kev faib khoom kub thiab kev hloov pauv ntawm lub crucible. (a) Kev faib tawm kub hauv lub crucible ntawm cov qauv 0 (sab laug) thiab qauv 1 (txoj cai) ntawm 0 h, chav tsev: ℃; (b) Kev faib tawm kub ntawm cov kab nruab nrab ntawm cov crucible ntawm cov qauv 0 thiab cov qauv 1 los ntawm hauv qab ntawm cov khoom siv raw mus rau cov noob siv lead ua ntawm 0 h; (c) Kub faib los ntawm qhov chaw mus rau ntug ntawm lub crucible ntawm cov noob siv lead ua nto (A) thiab raw khoom nto (B), nruab nrab (C) thiab hauv qab (D) ntawm 0 h, kab rov tav r yog qhov Cov noob siv lead ua lub vojvoog rau A, thiab cov khoom siv raw khoom siv lub vojvoog rau B ~ D; (d) Kev hloov kub ntawm qhov nruab nrab ntawm qhov nruab nrab (A), raw khoom nto (B) thiab nruab nrab (C) ntawm qhov loj hlob chamber ntawm cov qauv 0 thiab cov qauv 1 ntawm 0, 30, 60, thiab 100 h.
Daim duab 3 qhia txog kev thauj khoom ntawm lub sijhawm sib txawv hauv lub crucible ntawm cov qauv 0 thiab cov qauv 1. Cov pa roj theem cov khoom ntws ntawm cov khoom siv raw thiab cov khoom loj hlob tuaj nrog qhov nce ntawm txoj hauj lwm, thiab cov khoom thauj tsis muaj zog raws li kev loj hlob. . Daim duab 3 kuj qhia tau hais tias nyob rau hauv lub simulation tej yam kev mob, cov khoom raw ua ntej graphitizes nyob rau sab phab ntsa ntawm lub crucible thiab ces nyob rau hauv qab ntawm lub crucible. Tsis tas li ntawd, muaj recrystallization nyob rau saum npoo ntawm cov khoom siv raw thiab nws maj mam thickens raws li kev loj hlob. Daim duab 4(a) thiab 4(b) qhia tau hais tias cov khoom ntws ntawm cov khoom siv raw khoom txo qis thaum qhov kev loj hlob zuj zus, thiab cov khoom ntws ntws ntawm 100 h yog li 50% ntawm lub sijhawm pib; Txawm li cas los xij, tus nqi ntws yog qhov loj ntawm ntug vim qhov graphitization ntawm cov khoom siv raw, thiab qhov ntws ntawm ntug yog ntau tshaj 10 npaug ntawm qhov ntws ntawm qhov nruab nrab ntawm 100 h; Tsis tas li ntawd, cov nyhuv ntawm PG hauv cov qauv 1 ua rau cov khoom ntws ntawm cov khoom siv raw ntawm cov qauv 1 qis dua li ntawm cov qauv 0. Nyob rau hauv daim duab 4(c), cov khoom ntws nyob rau hauv ob qho tib si raw khoom cheeb tsam thiab lub txoj kev loj hlob chamber maj mam tsis muaj zog raws li qhov kev loj hlob zuj zus, thiab cov khoom ntws hauv cov khoom siv raw khoom txuas ntxiv txo qis, uas yog tshwm sim los ntawm kev qhib cua ntws channel ntawm ntug ntawm lub crucible thiab kev cuam tshuam ntawm recrystallization ntawm lub sab saum toj; nyob rau hauv lub chamber loj hlob, cov ntaub ntawv txaus tus nqi ntawm cov qauv 0 poob sai heev nyob rau hauv thawj 30 h mus rau 16%, thiab tsuas yog txo los ntawm 3% nyob rau hauv lub sij hawm tom ntej, thaum lub sij hawm tus qauv 1 tseem nyob ruaj khov nyob rau hauv cov txheej txheem kev loj hlob. Yog li ntawd, PG pab kom ruaj khov ntawm cov khoom ntws hauv cov khoom loj hlob. Daim duab 4(d) sib piv cov khoom ntws ntawm cov khoom siv lead ua loj hlob pem hauv ntej. Thaum lub sijhawm pib thiab 100 h, cov khoom thauj hauv cheeb tsam kev loj hlob ntawm cov qauv 0 yog qhov muaj zog dua li hauv cov qauv 1, tab sis ib txwm muaj qhov siab txaus ntawm thaj tsam ntawm ntug ntawm cov qauv 0, uas ua rau muaj kev loj hlob ntau ntawm ntug. . Lub xub ntiag ntawm PG nyob rau hauv cov qauv 1 zoo suppresses qhov tshwm sim.
Daim duab 3 Cov khoom ntws hauv lub crucible. Streamlines (sab laug) thiab tshaj tawm vectors (sab xis) ntawm cov khoom siv roj thauj hauv cov qauv 0 thiab 1 ntawm lub sijhawm sib txawv, qhov nrawm vector unit: m / s
Daim duab 4 Kev hloov pauv ntawm cov khoom ntws ntws. (a) Cov kev hloov pauv ntawm cov khoom ntws tus nqi faib nyob rau hauv nruab nrab ntawm cov khoom siv raw ntawm cov qauv 0 ntawm 0, 30, 60, thiab 100 h, r yog lub vojvoog ntawm cov khoom siv raw; (b) Cov kev hloov pauv ntawm cov khoom ntws tus nqi faib nyob rau hauv nruab nrab ntawm cov khoom siv raw ntawm cov qauv 1 ntawm 0, 30, 60, thiab 100 h, r yog lub vojvoog ntawm cov khoom siv raw; (c) Cov kev hloov pauv ntawm cov khoom ntws hauv lub chamber loj hlob (A, B) thiab hauv cov khoom siv raw (C, D) ntawm cov qauv 0 thiab 1 dhau sijhawm; (d) Cov ntaub ntawv ntws tus nqi faib nyob ze ntawm cov noob siv lead ua ntawm cov qauv 0 thiab 1 ntawm 0 thiab 100 h, r yog lub vojvoog ntawm cov noob siv lead ua
C / Si cuam tshuam rau crystalline stability thiab qhov tsis xws luag ntawm SiC siv lead ua kev loj hlob. Daim duab 5(a) muab piv rau C/Si piv faib ntawm ob lub qauv nyob rau lub caij pib. C / Si piv maj mam txo qis hauv qab mus rau sab saum toj ntawm lub crucible, thiab C / Si piv ntawm cov qauv 1 yog ib txwm siab dua li ntawm cov qauv 0 ntawm ntau txoj haujlwm. Cov duab 5(b) thiab 5(c) qhia tau hais tias qhov sib piv ntawm C / Si maj mam nce nrog kev loj hlob, uas yog cuam tshuam nrog kev nce hauv qhov kub thiab txias nyob rau theem tom ntej ntawm kev loj hlob, kev txhim kho ntawm cov khoom siv raw graphitization, thiab cov tshuaj tiv thaiv ntawm Si Cheebtsam hauv cov roj theem nrog cov graphite crucible. Hauv daim duab 5(d), C / Si piv ntawm cov qauv 0 thiab cov qauv 1 yog qhov sib txawv hauv qab PG (0, 25 mm), tab sis txawv me ntsis saum PG (50 mm), thiab qhov sib txawv maj mam nce thaum nws mus txog lub siv lead ua . Feem ntau, C / Si piv ntawm cov qauv 1 yog siab dua, uas yuav pab kom ruaj khov rau daim ntawv siv lead ua thiab txo qhov tshwm sim ntawm kev hloov theem.
Daim duab 5 Kev faib tawm thiab kev hloov pauv ntawm C/Si piv. (a) C/Si ratio faib nyob rau hauv crucibles qauv 0 (sab laug) thiab qauv 1 (txoj cai) ntawm 0 h; (b) C / Si piv ntawm qhov sib txawv ntawm cov kab nruab nrab ntawm crucible ntawm cov qauv 0 ntawm lub sijhawm sib txawv (0, 30, 60, 100 h); (c) C / Si piv ntawm qhov sib txawv ntawm cov kab nruab nrab ntawm crucible ntawm cov qauv 1 ntawm lub sijhawm sib txawv (0, 30, 60, 100 h); (d) Kev sib piv ntawm C / Si piv ntawm qhov sib txawv (0, 25, 50, 75, 100 mm) los ntawm cov kab nruab nrab ntawm crucible ntawm cov qauv 0 (khoom khov) thiab qauv 1 (dashed kab) ntawm lub sijhawm sib txawv (0, 30, 60, 100 h).
Daim duab 6 qhia tau hais tias qhov kev hloov ntawm particle inch thiab porosity ntawm raw khoom cheeb tsam ntawm ob lub qauv. Daim duab qhia tau hais tias cov khoom siv raw txoj kab uas hla txo qis thiab cov porosity nce nyob ze ntawm phab ntsa crucible, thiab ntug porosity tseem nce ntxiv thiab cov particle txoj kab uas hla txuas ntxiv txo qis thaum qhov kev loj hlob zuj zus. Qhov siab tshaj plaws porosity yog li 0.99 ntawm 100 h, thiab qhov tsawg kawg nkaus particle txoj kab uas hla yog li 300 μm. Lub particle txoj kab uas hla nce thiab lub porosity txo nyob rau saum npoo ntawm raw khoom, sib xws rau recrystallization. Lub thickness ntawm recrystallization cheeb tsam nce raws li kev loj hlob zuj zus, thiab cov particle loj thiab porosity hloov mus ntxiv. Qhov siab tshaj particle txoj kab uas hla mus txog ntau tshaj 1500 μm, thiab qhov tsawg kawg nkaus porosity yog 0.13. Tsis tas li ntawd, txij li thaum PG nce qhov kub ntawm cov khoom siv raw khoom thiab cov roj supersaturation me me, cov recrystallization thickness ntawm sab sauv ntawm cov khoom siv raw ntawm cov qauv 1 yog me me, uas txhim kho cov khoom siv raw khoom.
Daim duab 6 Kev hloov pauv ntawm cov kab nruab nrab (sab laug) thiab porosity (txoj cai) ntawm cov khoom siv raw ntawm cov qauv 0 thiab cov qauv 1 ntawm lub sijhawm sib txawv, particle inch unit: μm
Daim duab 7 qhia tau hais tias cov qauv 0 warps thaum pib ntawm kev loj hlob, uas tej zaum yuav muaj feem xyuam rau cov khoom siv ntau dhau los ntawm cov graphitization ntawm raw khoom ntug. Lub degree ntawm warping yog tsis muaj zog thaum lub sij hawm txoj kev loj hlob tom ntej, uas sib haum mus rau cov kev hloov nyob rau hauv cov ntaub ntawv txaus tus nqi nyob rau hauv pem hauv ntej ntawm lub crystal kev loj hlob ntawm cov qauv 0 nyob rau hauv daim duab 4 (d). Nyob rau hauv cov qauv 1, vim yog cov nyhuv ntawm PG, lub crystal interface tsis qhia warping. Tsis tas li ntawd, PG kuj ua rau kev loj hlob ntawm cov qauv 1 txo qis dua li ntawm cov qauv 0. Qhov nruab nrab thickness ntawm cov siv lead ua ntawm cov qauv 1 tom qab 100 h tsuas yog 68% ntawm cov qauv 0.
Daim duab 7 Interface hloov ntawm cov qauv 0 thiab cov qauv 1 muaju ntawm 30, 60, thiab 100 h
Crystal kev loj hlob tau ua tiav raws li cov txheej txheem ntawm cov lej simulation. Cov crystals loj hlob los ntawm cov qauv 0 thiab cov qauv 1 yog qhia hauv daim duab 8(a) thiab daim duab 8(b), feem. Cov siv lead ua ntawm cov qauv 0 qhia tau hais tias lub concave interface, nrog undulations nyob rau hauv nruab nrab cheeb tsam thiab ib theem hloov ntawm ntug. Qhov saum npoo convexity sawv cev rau qee qhov kev tsis sib haum xeeb hauv kev thauj cov khoom siv roj-theem, thiab qhov tshwm sim ntawm theem kev hloov pauv mus rau qhov qis C / Si piv. Lub interface ntawm cov siv lead ua loj hlob los ntawm cov qauv 1 yog me ntsis convex, tsis muaj theem hloov pauv, thiab cov tuab yog 65% ntawm cov siv lead ua tsis muaj PG. Feem ntau, cov txiaj ntsig kev loj hlob ntawm cov siv lead ua sib raug rau cov txiaj ntsig simulation, nrog rau qhov sib txawv ntawm qhov kub ntawm radial loj ntawm cov qauv siv lead ua 1, qhov kev loj hlob sai ntawm ntug yog suppressed, thiab tag nrho cov khoom ntws yog qeeb dua. Tag nrho cov qauv zoo ib yam nrog cov lej simulation.
Daim duab 8 SiC crystals loj hlob raws li qauv 0 thiab qauv 1
Xaus
PG yog qhov tsim nyog rau kev txhim kho tag nrho qhov kub thiab txias ntawm cov khoom siv raw thiab kev txhim kho ntawm axial thiab radial kub uniformity, txhawb nqa tag nrho sublimation thiab kev siv cov khoom siv raw; sab saum toj thiab hauv qab kub sib txawv nce, thiab radial gradient ntawm cov noob siv lead ua saum npoo nce, uas yuav pab tswj lub convex interface kev loj hlob. Hais txog kev hloov pauv huab hwm coj, kev taw qhia ntawm PG txo qis tag nrho cov huab hwm coj hloov pauv, cov khoom ntws ntawm cov khoom lag luam hauv cov chav loj hlob uas muaj PG hloov pauv tsawg dua nrog lub sijhawm, thiab tag nrho cov txheej txheem kev loj hlob yog ruaj khov. Nyob rau tib lub sijhawm, PG kuj tseem cuam tshuam qhov tshwm sim ntawm kev hloov pauv ntau dhau ntawm ntug. Tsis tas li ntawd, PG kuj nce qhov C / Si piv ntawm qhov kev loj hlob ib puag ncig, tshwj xeeb tshaj yog nyob rau sab pem hauv ntej ntawm cov noob siv lead ua cuam tshuam, uas yuav pab txo qis qhov tshwm sim ntawm theem hloov thaum lub sij hawm kev loj hlob. Nyob rau tib lub sijhawm, cov nyhuv thermal rwb thaiv tsev ntawm PG txo qhov tshwm sim ntawm recrystallization nyob rau sab sauv ntawm cov khoom siv raw rau qee yam. Rau kev loj hlob siv lead ua, PG slows down lub crystal kev loj hlob tus nqi, tab sis kev loj hlob interface yog ntau convex. Yog li, PG yog ib qho txiaj ntsig zoo los txhim kho kev loj hlob ib puag ncig ntawm SiC siv lead ua thiab ua kom zoo siv lead ua zoo.
Post lub sij hawm: Jun-18-2024