坩堝下降法生長紅外砷化镓晶體的研究
Growth of Infrared GaAs Crystal by Vertical Bridgman Method
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摘要: 利用坩堝下降法生長紅外砷化镓晶體, 坩堝下降爐控溫1260 ℃, 晶體以2.5mm/ h速度在溫度梯度為10 ℃/ cm的條件下結晶生長.PBN坩堝外壁黏附有氣相自發成核👨🔧、尺寸為1~3mm的砷化镓單晶顆粒.生長的砷化镓晶體直徑約50.8mm, 總長約140mm.晶體頭部放肩階段存在異相成核, 尾部出現多晶.截斷後獲得的砷化镓單晶長約100mm, 成晶率達70%.砷化镓單晶結晶質量良好, 頭尾平均位錯密度分別為868cm-2和1436cm-2, 電阻率達107 Ω· cm量級.砷化镓單晶整體紅外透過率約為55%, 接近最高理論透過率55.8%.滿足工業界使用要求.Abstract: The growth of infrared GaAs crystal is studied via the vertical Bridgman method. The pulling down furnace temperature is controlled at 1 260 ℃. GaAs crystal is grown at a rate of 2.5 mm/h under 10 ℃/cm temperature gradient. Some spontaneously nucleated GaAs single crystal particles with 1-3 mm size are found attach on the outside wall of PBN crucible. The grown GaAs crystal is about 50.8 mm in. diameter and about 140 mm in length. A heterogeneous nucleation is formed in the head of the crystal and some polycrystal is taken place in the tail part. The cut GaAs single crystal is about 100 mm in length and the overall crystalline rate is up to 70%. The obtained GaAs single crystal has excellent crystallization quality. The average etching pits density of the head and tail parts of the crystal is 868 cm-2 and 1 436 cm-2, respectively. The resistivity of the crystal is tested on the level of 107 Ω·cm. The infrared transmittance of the whole GaAs crystal is about 55% (nearly reaches the highest theory value 55. 8%), which can meet the requirements for industry application.