AB-INITIO PSEUDOPOTENTIAL CALCULATIONS OF INAS ALSB HETEROSTRUCTURES/

The InAs/AlSb heterojunction system is a lattice matched semiconductor heterostructure with type-II band alignment at the interfaces. This s ystem is attractive to ultrafast electronic device applications becaus e of its high mobility and large conduction-band offset. There are two different interfaces, i.e., AlAs-like or InSb-like, for InAs/AlSb het erostructure systems, with which very different properties, such as in terface roughness, mobility, and carrier concentrations, were found to be associated. There are experimental facts indicating preferential l ocal arrangements of the interfacial atoms. In this research, first pr inciple pseudopotential calculations are performed on InAs/AlSb superl attices associated with different interface arrangements, and their to tal energy is compared with that of superlattices with ideal sharp str ained interfaces. The results show that superlattices with switched la yers at the interfaces are more energetically favorable than superlatt ices with ideal sharp strained interfaces, the switching of the Al lay er with the In layer at the AlAs-like interface is the most energetica lly favorable, with about 0.08 eV lower energy for each switch. These calculations provide more understanding about the roughness at AlAs-li ke interfaces in InAs/AlSb superlattices. (C) 1997 American Institute of Physics.