Incorporation of Mg into thick free-standing HVPE GaN

Abstract

ABSTRACTMg, the only effectivep-type dopant for nitrides, is well-studied in thin films due to the important role the impurity plays in light emitting diodes and high power electronics. However, there are few reports of Mg in thick free-standing GaN substrates. Here we evaluate the material quality and point defects in GaN grown by hydride vapor phase epitaxy (HVPE) using metallic Mg as the doping source. The crystal quality is typical of commercially grown HVPE substrates, and the photoluminescence measurements reveal distinctively sharp excitonic and shallow-donor shallow-acceptor features. Secondary ion mass spectroscopy indicates total Mg concentrations between 7x1016and 6x1018cm-3in the four separate samples studied but, more significantly, photoluminescence and electron paramagnetic resonance spectroscopy show that the Mg is incorporated as a shallow acceptor.