A Universal Model for DX‐Center Binding Energy in Cubic III–V Compounds

Abstract

Based on the approach suggested by Chadi and Chang, a simple analytical model is suggested for estimating binding energies of DX‐centers in n‐type zinc‐blende semiconductor alloys with direct–indirect bandgap transition. Comparison of the model predictions with numerous experiments shows the only adjustable model parameter to be independent of either kind of n‐type impurity or particular alloy. Though the nature of such a universality is not completely clear, the model can be helpful for practical estimations and modeling/simulation of semiconductor devices utilizing the ternary and quaternary compounds. Application of the model to wide‐bandgap zinc‐blende semiconductors reveals a general trend of decreasing DX‐center binding energy with the bandgap, resulting in narrowing the composition range of alloys where DX‐center formation dominates over that of conventional shallow donors. Considering DX‐centers with multiple‐charge impurity statistics enables accurate calculation of free electron concentration and concentration of ionized impurities in the space‐charge regions.