Characterization of GaN synthesized in N-ion implanted GaAs

The hexagonal alpha-GaN phase (wurtzite) was synthesized in GaAs (001) by 70 keV N-2(+) ion implantation at 80 degrees C and subsequent furnace annealing at 850 degrees C for 10-30 min. N fluences used in this study were (2.0-3.2)x10(17) cm(-2) X-ray diffraction analysis revealed that a buried layer of wurtzite-GaN was produced. Raman spectra were observed at around 525 cm(-1) together with LO- and TO-phonons from the GaAs matrix, suggesting the existence of a A(1)(TO) mode in GaN. X-ray photoelectron spectroscopy analysis of the annealed samples also shows the peaks of Ga-2p3/2 (binding energy: 1117.1 eV) and N-1s (397.5 eV). A broad photoluminescence spectrum ranging from 350 nm (3.5 eV) to 450 nm (2.76 eV) was observed in the annealed samples, indicating both the near band edge emission (3.45 eV for wurtzite type GaN) and the impurity bands. (C) 1999 Elsevier Science B.V. All rights reserved.