作　　者： ; ; ;

机构地区： 内蒙古师范大学物理与电子信息学院物理学系

出　　处： 《发光学报》 2002年第5期456-460,共5页

摘　　要： 用经验赝势方法计算了体ZnSe以及ZnSe/GaAs单异质结系统中ZnSe外延层Γ、X、L等特殊对称点导带底能量随压力的变化。结果表明 ,同Si、Ge、GaAs等半导体材料不同 ,ZnSe的X点导带底具有正的压力系数 ,但比Γ点的压力系数小 ,这是ZnSe材料以及ZnSe基异质结构材料发生直接禁带向间接禁带的转变时所需转变压力较大的根本原因。研究了ZnSe/GaAs异质结构中晶格失配造成的应变对外延层Γ、X、L对称点压力系数的影响 。 It has been pointed out that the exponential decrease with pressure of the photoluminescence intensity around 3GPa observed in ZnSe/ZnCdSe superlattices and quantum wells can not be explained by the direct gap indirect gap transformation because the direct gap indirect gap transformation pressures are estimated as 13 7GPa for ZnSe and 7GPa for ZnSe/Zn 1-x Cd x Se( x =0 26) superlattices and quantum wells. But till now, no detailed calculations for the transformation pressures have been reported for the ZnSe based heterostructures. In order to understand better the properties of ZnSe and ZnSe based heterostructures under pressure, we studied the hydrostatic pressure dependence of the Γ,X and L energy band minima for bulk ZnSe and the ZnSe epilayer of ZnSe/GaAs heterostructures using the empirical pseudopotential method. The pseudopotential form factors at various pressures are obtained by scaling the atmospheric pseudopotential form factors in terms of the electron effective mass or the energy gap and the results show that the method of the energy gap scaling , which is proposed in this paper for the first time, is better than the electron effective mass scaling. The transformation pressures of bulk ZnSe and the ZnSe/GaAs epilayer are calculated as 13 5GPa and 9 5GPa with the energy gap scaling. By fitting the curves of the energy band minima versus pressure, we also obtained the pressure coefficients of the Γ,X and L energy band minima of bulk ZnSe. The corresponding pressure coefficients are 0 211 3eV/GPa , 0 071 4eV/GPa and 0 153 5eV/GPa respectively. It can be seen that the pressure coefficient of the X minima of ZnSe is positive, which is different from that of Si, Ge and GaAs semiconductor materials. On the other hand, the pressure coefficient of the X minima of ZnSe is smaller than that of the Γ minima, so the transformation from direct gap semiconductor to indirect gap semiconductor of bulk ZnSe can still occur but needs much gr

关 键 词： 静压 异质结构 直接禁带 间接禁带转变 压力系数 半导体材料 硒化锌 砷化镓 光致发光

领　　域： [理学] [理学] [理学] [理学]