Electronic properties of ordered alloys of zincblende (100) Zn_0.5Cd_0.5Se

The first theoretical results on the comparison of the electronic properties of Zn_0.5Cd_0.5Se prepared by means of two different methods, MBE (molecular beam epitaxy) and ALE (atomic layer epitaxy), are presented. In the former case, the material has layers with the two cations randomly distributed, while in the latter each layer is composed by a unique cation. The electronic band structures are calculated using the very well-known semi-empirical tight-binding approach, combined with the virtual crystal aproximation (VCA) in the first case; in the second case by extending the unit cell in order to introduce the two distinguished cation layers. Important differences are found in the electronic properties, depending on the growth method. The conduction band width narrows in the ordered "layer by layer" crystal. The orbital distribution is very different in both cases indicating also different optical transitions.