Effect of overgrowth conditions on the optical properties of lateral epitaxially overgrown a‐plane GaN
Badcock, T J and Haeberlen, M and Kappers, M J and Moram, M A and Dawson, P and Humphreys, C J and Oliver, R A
We investigate the optical properties of lateral epitaxially overgrown non-polar a -plane GaN using photoluminescence and spatially resolved cathodoluminescence spectroscopy. Despite the decreased density of extended defects relative to a-plane templates, in material overgrown at a low V:III ratio (57), the low temperature emission spectrum is very weak and is dominated by impurity bands centred at 2.92 and 2.25 eV. On subsequent overgrowth at a higher V:III ratio (260), the intensity of the near band edge emission increases by many orders of magnitude and a donor-acceptor pair band is seen. We suggest that the dramatic modification of the optical properties is related to the impurity or point-defect incorporation rate at the different V:III ratios employed.
Department of Materials
Imperial College London
Royal School of Mines
London, SW7 2AZ - UK