Dynamical Characteristics of Isolated Donors, Acceptors, and Complex Defect Centers in Novel ZnO

Abstract

Novel wide-bandgap ZnO, BeO, and ZnBeO materials have recently gained considerable interest due to their stellar optoelectronic properties. These semiconductors are being used in developing high-resolution, flexible, transparent nanoelectronics/photonics and achieving high-power radio frequency modules for sensors/biosensors, photodetectors/solar cells, and resistive random-access memory applications. Despite earlier evidence of attaining p-type wz ZnO with N doping, the problem persists in achieving reproducible p-type conductivity. This issue is linked to charging compensation by intrinsic donors and/or background impurities. In ZnO: Al (Li), the vibrational features by infrared and Raman spectroscopy have been ascribed to the presence of isolated AlZn(LiZn) defects, nearest-neighbor (NN) [AlZn−NO ] pairs, and second NN [AlZn−O−LiZn;VZn−O−LiZn] complexes. However, no firm identification has been established. By integrating accurate perturbation models in a realistic Green’s function method, we have meticulously simulated the impurity vibrational modes of AlZn (LiZn) and their bonding to form complexes with dopants as well as intrinsic defects. We strongly feel that these phonon features in doped ZnO will encourage spectroscopists to perform similar measurements to check our theoretical conjectures.