| In this dissertation, we used ab-initio full potential linear muffin-tin orbital (FP-LMTO) method to study native defects, chlorine and nitrogen doping, and chromium incorporation issues in ZnSe and ZnMgSe alloys. The method we used and the results we obtained are discussed in details.; In chapter 1, an introduction to recent studies in ZnSe was given. The methodology was discussed at chapter 2. In chapter 3, we studied lattice relaxation around native defects in ZnSe and formation energies for these native defects. Our results were compared with other theoretical results. In chapter 4, chlorine doping in ZnSe and ZnMgSe alloys are modeled, our results indicated that the addition of Mg reduces the formation energy for chlorine on the Se site, thereby predicting increased solubility. Subsequent chlorine doping experiments in ZnxMg1-xSe using molecular beam epitaxy indicated significantly higher chlorine incorporation in the presence of magnesium, directly supporting the prediction of the calculations. Our calculated results in maximum electron concentration in ZnMgSe with different Mg content also match experimental results very well. In chapter 5, we focus on chromium incorporation in ZnSe and ZnMgSe. Chromium site selection and charge selection in ZnSe were considered, and our results were consistent with experimental results. |
