Increased p-type conductivity through use of an indium surfactant in the growth of Mg-doped GaN

We have examined the effect of an indium surfactant on the growth of p-type GaN by ammonia-based molecular beam epitaxy. p-type GaN was grown at temperatures ranging from 700 to 780 degrees C with and without an indium surfactant. The Mg concentration in all films in this study was 4.5-6 x 10(19) cm(-3) as measured by secondary ion mass spectroscopy. All p-type GaN films grown with an indium surfactant had higher p-type conductivities and higher hole concentrations than similar films grown without an indium surfactant. The lowest p-type GaN room temperature resistivity was 0.59 Omega-cm, and the highest room temperature carrier concentration was 1.6 x 10(18) cm(-3). Fits of the temperature-dependent carrier concentration data showed a one to two order of magnitude lower unintentional compensating defect concentration in samples grown with the indium surfactant. Samples grown at higher temperature had a lower active acceptor concentration. Improvements in band-edge luminescence were seen by cathodoluminescence for samples grown with the indium surfactant, confirming the trends seen in the Hall data. (C) 2015 AIP Publishing LLC.