刻面
材料科学
外延
锗
位错
凝聚态物理
退火(玻璃)
半导体
密度泛函理论
曲面重建
各向同性腐蚀
结晶学
硅
化学物理
纳米技术
蚀刻(微加工)
光电子学
曲面(拓扑)
计算化学
化学
复合材料
几何学
物理
数学
图层(电子)
作者
Yiwen Zhang,Chuan Zhou,Ying Zhu,Guangrui Xia,Lei Li,Rui‐Tao Wen
摘要
Heteroepitaxial semiconductors such as Ge-on-Si are widely used in current opto-electronic and electronic applications, and one of the most important challenges for epitaxial Ge-on-Si is threading dislocations (TDs) in Ge layers caused by lattice mismatch between Ge and Si. Here, apart from traditional wet chemical etching, we report a convenient approach to evaluate the threading dislocation densities in heteroepitaxial layers through vacuum thermal annealing. More importantly, the controversial origin of thermal annealing induced pits on a Ge surface was addressed in this work. By combining both experiments and density functional theory (DFT) calculations, we find that the {111} facets defined thermal pits on Ge (001) surfaces are mainly caused by threading dislocation activation. Ge adatoms at the TD segments sublimate preferentially than the ones on dislocation-free Ge (001) surface regions, and its further evolution is determined by surface energies of {111} facets, leading to a construction of inverted pyramid-shaped thermal pits.
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