Thermal activation energies of Mg in GaN : Mg measured by the Hall effect and admittance spectroscopy

A series of GaN:Mg structures were grown in molecular beam epitaxy, using e ither one or two rf nitrogen sources, and in metalorganic chemical vapor de position systems with varying Mg flux. Acceptor energies were measured usin g the Hall effect and admittance spectroscopy techniques. The acceptor ener gies were found to be different for the two methods, i.e., 135-155 meV for the Hall effect measurement and 80-115 meV for the admittance spectroscopy measurement. The apparently small acceptor energies from the admittance spe ctroscopy measurement were explained, through a simulation process, by the combined effects of (1) high Mg acceptor concentration with no other free c arrier sources, and (2) the Mg emission kinetics assisted by the Frenkel-Po ole field effect in the GaN:Mg structures. (C) 2000 American Institute of P hysics. [S0021-8979(00)06616-0].