THEORY OF DOPING AND DEFECTS IN III-V NITRIDES

Doping problems in GaN and in AlGaN alloys are addressed on the basis of state-of-the-art first-principles calculations. For n-type doping w e find that nitrogen vacancies are too high in energy to be incorporat ed during growth, but silicon and oxygen readily form donors. The prop erties of oxygen, including DX-center formation, support it as the mai n cause of unintentional n-type conductivity. For p-type doping we fin d that the solubility of Mg is the main factor limiting the hole conce ntration in GaN. We discuss the beneficial effects of hydrogen during acceptor doping. Compensation of accepters by nitrogen vacancies may o ccur, becoming increasingly severe as x increases in AlxGa1 - xN alloy s. (C) 1998 Elsevier Science B.V. All rights reserved.