不同晶面与应变状态下Si／Ge应变异质界面的价带能量不连续性

VALENCE-BAND OFFSETS AT St/Ge STRAINED HETEROINTERFACES UNDER DIFFERENT STRAIN CONDITIONS

结合应变异质界面能带排列的平均键能理论和形变势方法，确定了三种不同衬底上生长的Ｓｉ／Ｇｅ系统在（００１）和（１１０）两种不同晶面上的价带能量不连续值（Ｅ＿ｖ）得出了Ｓｉ／Ｇｅ系统的Ｅ＿ｖ值随其衬底Ｓｉ＿ｌ－ｘＧｅ－ｘ的组分ｘ变化的定量关系结果表明，Ｓｉ／Ｇｅ系统价带平均能量的不连续性（Ｅ＿ｖ，ａｖ）基本不随应变状态的不同而变化，而最高价带的Ｅ＿ｖ值则表现出对弹性应变的高度敏感性（变化量约达０．５ｅＶ），此效应主要来源于单轴应力对价带结构的影响．Ｓｉ／Ｇｅ系统在（００１）面和（１０）面上的Ｅ＿ｖ值略有差别，表现出弱的晶格取向的相关性本文对（００１）面的计算结果与新近的归一保持赝势方法的大型超原胞计算结果以及相关的实验值相当一致．

This paper presents a theoretical determination of valence-band offsets (VBO' s) on(001 ) and (110) interfaces for St/Ge system under different strain conditions, by making useof an average bond energy theory in conjunction with a deformation potential method. Thequantitative relationship between the VBO's and the strain condition (characterized by thecomposition x in substrate Si_1-xGe-x ) is demonstrated. It is shown that the discontinuity be tween the two average valence-band energies is affected little by the strain condition, while,the discontinuity between the two tops of valence-band has a sensitive dependance on thestrain condition, and this effect is mainly due to the alteration of the valence-band structureInduced by the uniaxial stress. It is found that the VBO value on (110) interface is somewhatsmaller than those on (001 ) interface. i. e., there is a weak relevance to the lattice orienta tion. Present results of VBO's are 0. 74 eV for Ge on St(001 ) and 0. 22 eV for St on Ge(001 ), in very good agreement with experimental data f (0. 74 + 0. 13) eV and (0. 17 + 0. 13)eV, respectively.