Study of the effects of Mg and Be co-doping in GaN layers

GaN:Mg/AlGaN single heterostructures were grown on Si(111) substrates by plasma-assisted molecular beam epitaxy (PAMBE) leading to the fabrication of light emitting diodes (LEDs). p-type is successfully achieved using Mg, obtaining hole concentrations in the range of 1 x 10 (17) cm(-3). Although an intense and narrow (8 nm full width at half maximum) ultraviolet electroluminescence is observed under room temperature continuous-wave conditions, the electrical characteristics of the diode suffered mainly from a low p-type doping. In order to obtain higher hole concentrations and increase the performance of these devices, a study of the effects of Mg and Be co-doping is performed. Preliminary results show a decrease of the intensity of the yellow band in the photoluminescence spectra of co-doped samples in comparison with the Be-doped ones together with an increase of the intensity of the donor-acceptor pair related to the Be shallow acceptor. Both effects can be related to an increase in the p-type Be doping efficiency.