第一原理研究界面弛豫对InAs/GaSb超晶格界面结构、能带结构和光学性质的影响

通过广义梯度近似的第一原理全电子相对论计算, 研究了不同界面类型InAs/GaSb超晶格的界面结构、电子和光吸收特性. 由于四原子界面的复杂性和低对称性, 通过对InAs/GaSb超晶格进行电子总能量和应力最小化来确定弛豫界面的结构参数. 计算了InSb, GaAs型界面和非特殊界面(二者交替)超晶格的能带结构和光吸收谱, 考察了超晶格界面层原子发生弛豫的影响.为了证实能带结构的计算结果, 用局域密度近似和Hartree-Fock泛函的平面波方法进行了计算. 对不同界面类型InAs/GaSb超晶格的能带结构计算结果进行了比较, 发现界面Sb原子的化学键和离子性对InAs/GaSb超晶格的界面结构、 能带结构和光学特性起着至关重要的作用.

First-principles study of interface relaxation effects on interface structure, band structure and optical property of InAs/GaSb superlattices

The first-principles all electron relativistic calculations within the general gradient approximation are performed to investigate the interface structure, the electronic and the optical absorption properties of quaternary InAs/GaSb superlattices with InSb or GaAs type of interface. Because of the complexity and low symmetry of the quaternary interfaces, the equilibrium structural parameters of relaxed interfaces are determined by the minimization of total electronic energy and strain in InAs/GaSb superlattices. The band structures and the optical absorption spectra of InAs/GaSb superlattices with special InSb or GaAs and normal (two types are alternate) interfaces are calculated, with the consideration of the superlattice interface atomic relaxation effects. The calculation of relativistic Hartree-Fock functional and local density approximation with the plane wave method is also implemented to demonstrate the calculated band structure results. The calculated band structures of InAs/GaSb superlattices with different types of interfaces are systematically compared. We find that the chemical bonding and ionicity of interfacial Sb atoms are essentially important in determining the interface structures, the band structures and the optical properties of InAs/GaSb superlattices.