Chemical trends for deep antisite defect levels in III –V compounds

Abstract

Chemical trends for all deep antisite defect levels which are expected to lie within or close to the main energy gap are presented for nine III-V compounds. We use a previously presented rescaled defect-molecule model to select the relevant levels and calculate their position by extrapolating from available experimental data in GaAs. Charge-state effects as well as symmetry-conserving lattice distortions are included qualitatively. Anion antisite defects are fourd to produce deep A 1 levels within the main energy gap and T 2 levels close to the conduction band edge. For most of the investigated compounds we find that cation antisite defects induce deep T 2 levels which lie within the forbidden energy gap. No other deep sp 3-type levels are expected to lie within or close to the main energy gap. Both the prediction and the calculated positions of these levels are in good agreement with previous calculations and the few experimental data available. The predicted chemical trends agree well with those obtained previously by tight-binding models, where available. This is quite remarkable because our model is mainly based on a simple rescaling assumption similar to that of tight-binding models, but does not require a detailed information on the band structure of the host.