Studies of deep centers in high-resistivity p-GaN films doped with Zn and grown on SIC by hydride vapor phase epitaxy

The results of deep levels studies in high-resistivity p-GaN films doped wi th Zn and grown by hydride vapor phase epitaxy on SiC are presented. These studies show the presence of deep traps with apparent activation energies o f 0.4, 0.6 and 0.9 cV. Conductivity versus temperature measurements suggest that the Fermi level in the films is pinned near E-v + 0.9 eV. From the 0. 3, 0.6 and 0.9 eV traps the 0.4 and the 0.9 eV traps are argued to be hole traps in the lower half of the bandgap while the 0.6 eV traps are quite sim ilar to the well known electron traps in the upper half of the bandgap. Mic rocathodoluminescence (MCL) spectra measurements show the presence of band edge luminescence and of two defect bands at 2.2 and 2.8 eV (the yellow ban d and the blue band). MCL imaging of the samples indicated also a formation of a network of bright line defects presumably near the GaN/SiC interface. (C) 2001 Elsevier Science Ltd. All rights reserved.