Predictive Computations of Properties of Wide-Gap and Nano- Semiconductors

摘要

We report the progress made in the implementation of the afore- mentioned project. To date, we have strictly adhered to the provisions in the proposal relative to the research personnel, materials under study, and the overall research tasks (i.e., computations and theoretical analysis). We have consequently generated new knowledge that is reported in several articles. Twelve (12) articles have already been published, including six (6) in refereed journals and four (4) in refereed conference proceedings. These articles are appended to this report. We have made fourteen (14) technical presentations on our findings, including at two (2) national and two (2) international conferences. The utter significance of our findings resides in the fact that they have confirmed our resolution of a long-standing problem in materials science stemming from a 30 to 50% or more underestimation, by theory, of the measured energy gaps (atoms, molecules, and clusters) and band gaps (semiconductors and insulators). Specifically, density functional theory (DFT) and its local density approximation (LDA) had been blamed, before our work, for the resulting gross disagreements between theory and experiment. Unlike previous works, we have obtained the experimentally measured band gaps of wurtzite InN, ZnO, and of several single walled carbon nanotubes. This feat was accomplished by our utilization of the Bagayoko, Zhao, and Williams (BZW) method. Further, we have predicted the band gap of cubic InN for which no experimental results are available. It is befitting that this ONR funded project exonerated DFT and LDA that were obtained by a project funded by ONR and for which Dr. Walter Kohn received the 1998 Nobel Prize in Chemistry.