Ainihin tsari naSiCcrystal girma ya kasu kashi sublimation da bazuwar albarkatun kasa a high zafin jiki, sufuri na gas lokaci abubuwa a karkashin mataki na zafin jiki gradient, da kuma recrystallization girma na gas lokaci abubuwa a iri crystal. Bisa ga wannan, ciki na crucible ya kasu kashi uku: yanki na albarkatun kasa, ɗakin girma da crystal iri. An zana samfurin siminti na lamba bisa ainihin juriyaSiCKayan aikin haɓaka kristal guda ɗaya (duba hoto 1). A cikin lissafi: kasa nacrucibleshine 90 mm nesa daga kasa na gefen hita, saman zafin jiki na crucible ne 2100 ℃, da albarkatun kasa diamita ne 1000 μm, da porosity ne 0.6, da girma matsa lamba ne 300 Pa, da kuma girma lokaci ne 100 h. . Kauri na PG shine 5 mm, diamita yana daidai da diamita na ciki na crucible, kuma yana 30 mm sama da albarkatun kasa. Ana yin la'akari da tsarin sublimation, carbonization, da recrystallization na yankin albarkatun ƙasa a cikin lissafi, kuma ba a la'akari da martani tsakanin PG da abubuwan lokaci na gas. Ana nuna sigogin abubuwan da ke da alaƙa da ƙididdiga a cikin Tebur 1.
Hoto 1 Samfurin lissafin kwaikwaiyo. (a) Samfurin filin thermal don simintin haɓakar crystal; (b) Rarraba yankin ciki na crucible da matsalolin jiki masu alaƙa
Table 1 Wasu sigogi na zahiri da aka yi amfani da su a cikin lissafin
Hoto na 2 (a) yana nuna cewa yanayin zafin tsarin da ke ɗauke da PG (wanda aka nuna a matsayin tsarin 1) ya fi na tsarin kyauta na PG (wanda aka nuna a matsayin tsarin 0) ƙasa da PG, kuma ƙasa da na tsarin 0 sama da PG. Gabaɗayan yanayin zafin jiki yana ƙaruwa, kuma PG yana aiki azaman wakili mai hana zafi. Bisa ga Figures 2 (b) da 2 (c), axial da radial zafin jiki gradients na tsarin 1 a cikin albarkatun kasa yanki ne karami, da yawan zafin jiki rarraba ne mafi uniform, da sublimation na abu ne mafi cikakken. Ba kamar yankin albarkatun ƙasa ba, Hoto 2 (c) yana nuna cewa radial zafin jiki gradient a iri crystal na tsarin 1 ya fi girma, wanda za a iya lalacewa ta hanyar daban-daban rabbai na daban-daban zafi canja wurin yanayi, wanda ke taimaka crystal girma tare da convex dubawa. . A cikin hoto na 2 (d), yanayin zafi a wurare daban-daban a cikin kullun yana nuna haɓakar haɓaka yayin da girma ya ci gaba, amma bambancin zafin jiki tsakanin tsarin 0 da tsarin 1 yana raguwa a hankali a cikin yanki na albarkatun kasa kuma a hankali yana karuwa a cikin ɗakin girma.
Hoto 2 Rarraba zafin jiki da canje-canje a cikin crucible. (a) Rarraba yawan zafin jiki a cikin crucible na tsarin 0 (hagu) da tsarin 1 (dama) a 0 h, naúrar: ℃; (b) Rarraba zafin jiki a kan tsakiyar layin crucible na tsarin 0 da tsarin 1 daga kasan albarkatun kasa zuwa crystal iri a 0 h; (c) Rarraba zafin jiki daga tsakiya zuwa gefen crucible a kan nau'in crystal surface (A) da kuma albarkatun kasa (B), tsakiya (C) da kasa (D) a 0 h, a kwance axis r ne radius crystal iri don A, da radius yanki na albarkatun ƙasa don B ~ D; (d) Canjin yanayin zafi a tsakiyar babban ɓangaren (A), albarkatun ƙasa (B) da tsakiya (C) na ɗakin girma na tsarin 0 da tsarin 1 a 0, 30, 60, da 100 h.
Hoto na 3 yana nuna jigilar kayayyaki a lokuta daban-daban a cikin ƙugiya na tsarin 0 da tsarin 1. Tsarin gas na gas a cikin yanki na albarkatun kasa da ɗakin girma yana ƙaruwa tare da karuwar matsayi, kuma jigilar kayan yana raunana yayin da girma ya ci gaba. . Hoto na 3 kuma yana nuna cewa a ƙarƙashin yanayin simintin, albarkatun ƙasa na farko suna zana hoto akan bangon gefe na crucible sannan kuma a ƙasan crucible. Bugu da kari, akwai recrystallization a saman albarkatun kasa kuma a hankali yana kauri yayin da girma ya ci gaba. Figures 4 (a) da 4 (b) sun nuna cewa adadin kayan da ke cikin kayan aiki yana raguwa yayin da girma ya ci gaba, kuma adadin kayan aiki a 100 h shine kusan 50% na lokacin farko; duk da haka, yawan ruwa yana da girma sosai a gefen saboda graphitization na albarkatun kasa, kuma yawan gudu a gefen ya fi sau 10 fiye da yadda ya kamata a cikin tsakiyar yanki a 100 h; Bugu da ƙari, tasirin PG a cikin tsari na 1 yana sa ƙimar kayan aiki a cikin yanki na kayan aiki na tsarin 1 ƙasa da na tsarin 0. A cikin hoto 4 (c), abubuwan da ke gudana a cikin duka yanki na albarkatun ƙasa da kuma ɗakin girma a hankali yana raunana yayin da girma ya ci gaba, kuma kayan da ke gudana a cikin yanki na kayan aiki ya ci gaba da raguwa, wanda ya haifar da bude tashar tashar iska a gefen crucible da kuma hana recrystallization a saman; a cikin ɗakin girma, ƙimar kayan aiki na tsarin 0 yana raguwa da sauri a farkon 30 h zuwa 16%, kuma kawai yana raguwa da 3% a cikin lokaci mai zuwa, yayin da tsarin 1 ya kasance mai inganci a duk tsawon tsarin girma. Sabili da haka, PG yana taimakawa wajen daidaita yawan kwararar kayan abu a cikin ɗakin girma. Hoto na 4 (d) yana kwatanta yawan kwararar kayan abu a gaban ci gaban crystal. A farkon lokacin da 100 h, jigilar kayan abu a cikin yanki na haɓakar tsarin 0 ya fi karfi fiye da haka a cikin tsarin 1, amma akwai ko da yaushe babban yanki mai girma a gefen tsarin 0, wanda ke haifar da girma mai yawa a gefen. . Kasancewar PG a cikin tsari na 1 yana murkushe wannan lamarin yadda ya kamata.
Hoto na 3 Gudun kayan aiki a cikin crucible. Streamlines (hagu) da vectors vectors (dama) na jigilar kayan gas a cikin tsarin 0 da 1 a lokuta daban-daban, naúrar vector velocity: m/s
Hoto 4 Canje-canje a cikin adadin kwararar kayan. (a) Canje-canje a cikin rabon rabon kayan aiki a tsakiyar kayan aikin 0 a 0, 30, 60, da 100 h, r shine radius na yanki na albarkatun kasa; (b) Canje-canje a cikin rarraba rabon kayan aiki a cikin tsakiyar kayan aiki na tsarin 1 a 0, 30, 60, da 100 h, r shine radius na yanki na albarkatun kasa; (c) Canje-canje a cikin adadin kwararar kayan cikin ɗakin girma (A, B) da cikin albarkatun ƙasa (C, D) na tsarin 0 da 1 akan lokaci; (d) Rarraba ƙimar kayan abu kusa da saman kristal iri na sifofi 0 da 1 a 0 da 100 h, r shine radius na kristal iri.
C/Si yana shafar kwanciyar hankali da ƙarancin ƙarancin ci gaban SiC crystal. Hoto na 5 (a) ya kwatanta rabon rabon C/Si na sifofi biyu a farkon lokacin. Matsakaicin C / Si a hankali yana raguwa daga ƙasa zuwa saman crucible, kuma ƙimar C / Si na tsarin 1 koyaushe yana sama da na tsarin 0 a wurare daban-daban. Figures 5 (b) da 5 (c) sun nuna cewa rabon C / Si a hankali yana ƙaruwa tare da girma, wanda ke da alaƙa da haɓakar zafin jiki na ciki a cikin mataki na gaba na girma, haɓakar graphitization albarkatun kasa, da kuma amsawar Si aka gyara a cikin gas lokaci tare da graphite crucible. A cikin Hoto 5 (d), ma'aunin C / Si na tsarin 0 da tsarin 1 sun bambanta da yawa a ƙasa PG (0, 25 mm), amma dan kadan ya bambanta sama da PG (50 mm), kuma bambancin yana ƙaruwa yayin da yake gabatowa da crystal. . Gabaɗaya, rabon C / Si na tsarin 1 ya fi girma, wanda ke taimakawa daidaita sigar crystal da rage yuwuwar canjin lokaci.
Hoto 5 Rarraba da canje-canje na rabon C/Si. (a) Rarraba rabo C / Si a cikin crucibles na tsarin 0 (hagu) da tsarin 1 (dama) a 0 h; (b) C / Si rabo a nisa daban-daban daga tsakiyar layi na crucible na tsarin 0 a lokuta daban-daban (0, 30, 60, 100 h); (c) C / Si rabo a nisa daban-daban daga tsakiyar layi na crucible na tsarin 1 a lokuta daban-daban (0, 30, 60, 100 h); (d) Kwatanta rabon C/Si a nisa daban-daban (0, 25, 50, 75, 100 mm) daga tsakiyar layin crucible na tsarin 0 (layi mai ƙarfi) da tsarin 1 (layin dage) a lokuta daban-daban (0, 30, 60, 100 h).
Hoto 6 yana nuna canje-canje a diamita na barbashi da porosity na yankunan albarkatun ƙasa na sifofin biyu. Adadin ya nuna cewa diamita na kayan albarkatun ƙasa yana raguwa kuma porosity yana ƙaruwa kusa da bangon da ba a iya gani ba, kuma gefen gefen yana ci gaba da karuwa kuma diamita na barbashi yana ci gaba da raguwa yayin da girma ya ci gaba. Matsakaicin porosity gefen shine game da 0.99 a 100 h, kuma mafi ƙarancin diamita shine kusan μm 300. A barbashi diamita ƙara da porosity rage a kan babba surface na albarkatun kasa, m recrystallization. A kauri daga cikin recrystallization yankin yana ƙaruwa yayin da girma ci gaba, da barbashi size da porosity ci gaba da canzawa. Matsakaicin diamita na barbashi ya kai fiye da 1500 μm, kuma mafi ƙarancin porosity shine 0.13. Bugu da ƙari, tun da PG yana ƙara yawan zafin jiki na yanki na kayan aiki kuma gas supersaturation yana da ƙananan, recrystallization kauri daga cikin babba na albarkatun kasa na tsarin 1 ƙananan ne, wanda ke inganta ƙimar amfani da albarkatun kasa.
Hoto 6 Canje-canje a cikin diamita barbashi (hagu) da porosity (dama) na yanki na albarkatun ƙasa na tsarin 0 da tsarin 1 a lokuta daban-daban, sashin diamita barbashi: μm
Hoto na 7 ya nuna cewa tsarin 0 warps a farkon girma, wanda zai iya kasancewa yana da alaƙa da yawan kwararar kayan abu wanda ya haifar da graphitization na gefen albarkatun kasa. Matsayin yaƙe-yaƙe yana raunana yayin tsarin ci gaba na gaba, wanda ya dace da canjin yanayin kwararar kayan abu a gaban ci gaban crystal na tsarin 0 a cikin Hoto 4 (d). A cikin tsarin 1, saboda tasirin PG, ƙirar crystal baya nuna warping. Bugu da kari, PG kuma yana sanya girman girman tsarin 1 ya ragu sosai fiye da na tsarin 0. Kauri na tsakiya na kristal tsarin 1 bayan 100 h shine kawai 68% na tsarin 0.
Hoto 7 Canje-canje na mu'amala na tsarin 0 da tsarin 1 lu'ulu'u a 30, 60, da 100 h
An gudanar da haɓakar kristal a ƙarƙashin yanayin tsari na simintin ƙididdiga. Lu'ulu'u da aka girma ta tsarin 0 da tsarin 1 ana nuna su a cikin Hoto 8 (a) da Hoto 8 (b), bi da bi. Ƙa'idar tsarin 0 yana nuna ƙirar ƙira, tare da undulations a cikin tsakiyar yanki da canjin lokaci a gefen. Matsakaicin yanayin yana wakiltar wani matakin rashin daidaituwa a cikin jigilar kayan-lokacin gas, kuma abin da ya faru na canjin lokaci ya yi daidai da ƙarancin C / Si. Ma'anar kristal da aka girma ta hanyar tsarin 1 yana da ɗan ƙaramin ƙarfi, ba a sami canjin lokaci ba, kuma kauri shine 65% na crystal ba tare da PG ba. Gabaɗaya, sakamakon ci gaban kristal ya dace da sakamakon kwaikwayo, tare da babban bambancin zafin jiki na radial a ƙirar ƙira na tsari 1, saurin girma a gefen yana danne, kuma yawan kwararar kayan abu yana da hankali. Yanayin gaba ɗaya ya yi daidai da sakamakon simintin ƙididdiga.
Hoto 8 SiC lu'ulu'u masu girma a ƙarƙashin tsari 0 da tsari 1
Kammalawa
PG yana da kyau don inganta yawan zafin jiki na yanki na kayan aiki da kuma inganta daidaituwa na axial da radial zafin jiki, inganta cikakken sublimation da amfani da albarkatun kasa; bambance-bambancen zafin jiki na sama da ƙasa yana ƙaruwa, kuma radial gradient na nau'in crystal surface yana ƙaruwa, wanda ke taimakawa wajen ci gaba da haɓakar haɓakar haɗin gwiwa. Dangane da canja wurin taro, gabatarwar PG yana rage yawan canjin taro na gabaɗaya, yawan kwararar kayan abu a cikin ɗakin haɓaka mai ɗauke da PG yana canzawa ƙasa da lokaci, kuma duk tsarin haɓaka yana da kwanciyar hankali. A lokaci guda, PG kuma yana hana abin da ya faru na wuce gona da iri na canja wurin taro. Bugu da ƙari, PG kuma yana ƙara ƙimar C / Si na yanayin girma, musamman a gefen gaba na ƙirar ƙira na iri, wanda ke taimakawa wajen rage abin da ya faru na canjin lokaci a lokacin tsarin girma. A lokaci guda, tasirin tasirin thermal na PG yana rage abin da ya faru na recrystallization a cikin babban ɓangaren albarkatun ƙasa zuwa wani yanki. Don haɓakar kristal, PG yana rage saurin haɓakar kristal, amma haɓakar haɓakar haɓakar ya fi rikitarwa. Sabili da haka, PG hanya ce mai tasiri don haɓaka yanayin ci gaban lu'ulu'u na SiC da haɓaka ingancin kristal.
Lokacin aikawa: Juni-18-2024