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Crystal quality and impurity segregation of semiconductor crystals grown under microgravity

微重力下生长的半导体晶体的晶体质量和杂质偏析

基本信息

批准号：
06452106
负责人：
NISHIMAGA Tatau
金额：
$ 1.09万
依托单位：
University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

GaSb single crystal grown by Chinese recoverable satellite No.14 was characterized by chemical etching and spatially resolved photoluminescence. The crystal doped with Te was grown by Bridgman technique under microgravity. The grown crystal was cut longitudinally along the growth direction <111>, into two parts and among them one piece was further cut perpendicular to the growth direction. Each sample was polished mechanically and chemically etched to reveal impurity striations, twin or grain boundaries and dislocations. It was demonstrated that impurity striations are present in the earth grown part while they are absent in space grown part. It was also found that the dislocation density goes to zero in the space grown part where the melt did not touch with the ampoule wall but it increases steeply in the part where strong contact with the wall occured.The concentration distribution of Te was measured by using the spatially resolved photoluminescence (SRPL). The measurements of spatially resolved photoluminescence were carried out point by point from the earth grown seed part to the regrown part along the growth direction. It was found that the concentration of Te decreases abruptly at the interface between the seed ant the regrown part. Then, it increases rapidly to the impurity level of the seed region. The profile shows that the impurity doping occured in pure diffusion control and this suggests that Marangoni convection was stopped as well as the thermal convection.

用化学腐蚀和空间分辨光致发光对我国14号返回式卫星生长的GaSb单晶进行了表征。用Bridgman法在微重力条件下生长了掺Te的晶体。生长的晶体沿生长方向被纵向切割成两部分，其中一块垂直于生长方向被进一步切割。每个样品都经过机械抛光和化学腐蚀，以揭示杂质条纹、孪晶或晶界和位错。结果表明，在地球生长部分存在杂质条纹，而在空间生长部分没有杂质条纹。研究还发现，在空间生长部分，熔体未接触安瓶壁处的位错密度接近于零，而在与安瓶壁强接触的部分，位错密度急剧增加。空间分辨光致发光的测量是沿着生长方向从大地生长的种子部分到再生部分逐点进行的。结果发现，在种子和再生部分之间的界面上，Te的浓度急剧下降。然后，它迅速增加到种子区的杂质水平。剖面图显示，杂质掺杂发生在纯扩散控制中，这表明Marangoni对流和热对流都被停止了。