OPTICAL AND ELECTRICAL-PROPERTIES OF HIGH-TEMPERATURE ANNEALED HETEROEPITAXIAL GAN-MG LAYERS

In this paper we present for the first time luminescence and electrica l measurements of GaN:Mg heteroepitaxial layers annealed at very high temperatures up to 1500 degrees C and at high pressures of nitrogen up to 16 kbar. The presence of high nitrogen pressure prevents GaN from thermal decomposition. It was found that annealing in the presence of additional Mg atmosphere leads to a high quality p-type epitaxial laye r of the hole concentration equal to 2 x 10(17) cm(-3) and mobility 16 cm(2)/(V s). However, annealing at high temperatures without addition al magnesium causes conversion to n-type. It is also shown that in the high temperature annealed GaN:Mg epilayers the donor-acceptor lumines cence is the dominant recombination channel.