ABSTRACT
Defects play very important role in semiconductors and, in many cases, they determine the electronic and optoelectronic properties of the host materials. This is especially true for the dilute nitrides, which are caused by the intrinsically large size and chemical mismatch between the first-row nitrogen and other group V elements such as P, As, and Sb. As a result, the equilibrium solubility of N in the dilute nitrides is extremely low, and the
minority-carrier lifetime is notoriously small in comparison with conventional semiconductor alloys, hindering many potential applications. Recently, first-principles theory has been developed to unveil the physical properties of the various defects such as vacancies, antisites, split-interstitials, as well as the complexes involving hydrogen. These studies show that the defect physics of the dilute nitrides is qualitatively different from that of conventional semiconductors, due to interaction with or between nitrogen atoms. This has led to a whole range of new physical phenomena, ranging from the existence of a new class of intrinsic deep traps involving N pairs (and possibly clusters) to a surprising modification of the band gap by hydrogen. Epitaxial growth conditions that enhance the N incorporation while maintaining a low density of intrinsic defects are also elucidated.
