Reactivation of Mg acceptor in Mg-doped GaN by nitrogen plasma treatment

Mg-doped GaN films, grown by metalorganic chemical vapor deposition, were t reated with a nitrogen plasma after a conventional rapid thermal annealing (RTA). The conductivity of the p-type GaN film was greatly enhanced by nitr ogen plasma treatment, and exhibited a higher sheet hole concentration as w ell as lower sheet resistance than the RTA samples. A photoluminescence (PL ) band which peaked at 3.27 eV was new, and a band at 2.95 eV was markedly attenuated in the plasma treated samples. PL measurements suggest that self -compensation in a Mg-doped GaN caused by the nitrogen vacancies is effecti vely reduced by the nitrogen plasma treatment, leading to an enhanced p-typ e conductivity. In addition, the plasma-treated sample revealed a drastic r eduction in specific contact resistance by three orders of magnitude, compa red with the RTA samples. (C) 2000 American Institute of Physics. [S0003- 6 951(00)05021-X].