Formation mechanism of grown-in defects in Czochralski germanium crystal growth

锗(Ge)有望作为高速ULSI器件和III-V基太阳能电池的衬底或底部电池的材料。本研究对提拉法生长的Ge晶体中的位错、沉淀物和空洞等内生缺陷进行了实验研究，探讨了这些缺陷的形成机理，成功地生长出了无位错的Ge晶体，并提出了新的生长工艺。B在Ge中的平衡偏析系数为6.2。当Ge晶体中As含量超过1×10^&lt；19&gt；cm^&lt；-3&gt；时，沿{111}晶面形成片状的GeAs析出物。

Germanium (Ge) has been expected as materials for high-speed ULSI devices and for the substrate or the bottom cell of III-V-based solar cells. In this study, grown-in defects, such as dislocation, precipitates and void, in Ge crystals grown by the Czochralski (CZ) method were experimentally evaluated and formation mechanisms of such defects were investigated.As typical results, we succeeded in growing dislocation-free Ge crystals, and the new growth technique was proposed. An equilibrium segregation coefficient of B in Ge was found to be 6.2. When As concentration in a Ge crystal exceeded 1×10^<19>cm^<-3>, plate-like GeAs precipitates were formed along {111} plane.