Self-consistent tight-binding total energy calculations: Application to GaAs/Si and ZnSe/GaAs (100) interfaces

Abstract

Self-consistent tight-binding total energy calculations are performed for various models of GaAs/Si and ZnSe/GaAs (100) interfaces. A graded GaAs/Si interface with the first monolayer on substrate having 1 As atom per 3 Si atoms followed by a second monolayer with 3 Ga atoms per 1 Si atom and continued with 2 bulk-like As and Ga monolayers is found to be structurally more stable than other interfaces. The instability of the abrupt interface is driven by elastic rather than electrostatic forces. Similar results are obtained for the ZnSe/GaAs (100) interface. The graded interface with Ga atoms exchanged against Zn atoms is found to be energetically most stable. Strong macroscopic electric fields are found in the surface and interface regions for both the GaAs/Si and ZnSe/GaAs interfaces.