平均键能方法在应变层异质结带阶计算中的简化模型  

Simplified Model of Average-bond Energy Method in Calculating Band Offset of Strained-layer Heterojunction

作　　者：廖任远[1] 蔡淑惠[1] 郑永梅[1] 王仁智[1] 李书平[1] 

机构地区：[1]厦门大学物理系,福建厦门361005

出　　处：《发光学报》2001年第2期182-186,共5页Chinese Journal of Luminescence

基　　金：福建省自然科学基金资助项目 (E990 0 0 5 )

摘　　要：将平均键能方法推广应用于应变层异质结的价带和导带阶研究。通过平均带阶参数形变势amv来研究带阶参数Emv随应变状态的变化关系 ,发现平均带阶参数Emv .av=Em-Ev .av在不同应变状态下基本上保持不变。因此 ,在应变层带阶参数Emv的计算中 ,只需计算其发生应变前体材料的带阶参数Emv .0 值并引用形变势b和SO裂距Δ0 的实验值 ,通过简便的代数运算即可得到应变层的Emv值 ,从而方便地预言不同应变层异质结的价带带阶。本文引入带隙形变势aGap来描述带隙改变量ΔEg 随应变状态的变化。由导带带阶和价带带阶的关系ΔEc=ΔEg+ΔEv 可以求出不同应变情况下的导带带阶。One of the model theories for band aligning is average bond energy model,in which the average bond energy is used as a reference level for determining valence band offsets.Since the model has been proved quite successful in determining band offsets of lattice matched heterojunctions,here we extended it to study band offsets of strained layer heterojunctions.Through a careful study of band offset parameter E mv with deformation potential a mv ,we found that the averge band offset parameter E mv.av ( E mv.av = E m - E v.av ) almost kept unchanged under different strain conditions,which is one of the main features of average bond energy method.Therefore,to obtain strained layer band offset parameter E mv ,only the unstrained band offset parameter E mv.0 ,deformation potential parameter b and the experimental value of spin orbit splitting Δ 0 are necessary for simple algebraic operations.Obviously,it will be very convenient for calculating valence band offsets of strained layer heterojunctions,since it doesn't need to consider the exact strain characteristics.In addition,we introduced deformation potential of band gap a Gap to describe the change of band gap under different strain states.Based on the relationship between conduction band offset and valence band offset (Δ E c=Δ E \-g+Δ E \-v),it is easy to calculate conduction band offsets of heterojunctions under different strain conditions.Our calculated band offsets of several common strained layer heterojunctions are fairy good compared to those obtained by CNL or MST method,and in good agreement with experimental data.To sum up,our method is an effective and simple way in determining band offsets of strained layer heterojunctions.

关 键 词：带阶 平均键能 异质结 应变层 半导体 能级 

分 类 号：O471.5[理学—半导体物理]