Résumé
In this paper we present the resistivity and Hall-effect measurements on p-type GaN doped with Mg. The experiments were carried out as a function of hydrostatic pressure Lip to 1200 MPa in the temperature range 260-400 K. Both bulk GaN crystals as well as GaN: Mg epilayers were studied. In the investigated samples the decrease of resistivity and increase of hole concentration under pressure was observed. Such a behavior, which is contrary to the n-type material strongly suggests a decrease of the ionization energy of Mg acceptor (E-a = 183 meV) with pressure. This shift is very weak, less than -2 meV/GPa. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim