Control of Mg doping of GaN in RF-plasma molecular beam epitaxy

We studied the influence of the growth temperature and Mg flux on the morphology, polarity inversion and p-type conductivity in GaN:Mg layers grown by plasma-assisted molecular beam epitaxy (PAMBE). Polarity-dependent wet etching, secondary ion mass spectroscopy and transmission electron microscopy are used to determine the polarity inversion of heavily M.-doped GaN layers. Phase diagram for polarity inversion effect as a function of substrate temperature and Mg flux is presented. The maximum hole concentration measured in Hall effect experiments is 5 x 10(17) cm(-3) for Mg concentration of 10(20) cm(-3). (c) 2005 Elsevier B.V. All rights reserved.