Non-planar selective area growth and characterization of GaN and AlGaN

Non-planar selective area growth of GaN and Al0.1Ga0.9N was performed by metalorganic chemical vapor deposition, on selectively etched GaN samples masked with SiO2 and AlN. Simultaneous growth on bottom surface and etched side walls occurred, resulting features extending in height above the etched mesa near the mask edge. For GaN, a significant mask-diffusion enhanced growth rate was observed, while for Al0.1Ga0.9N the enhancement was insignificant. The Al composition was investigated near the mask edge, with spectrally resolved cathodoluminescence microscopy, and was found to be lower within 0.6 mum of the mask edge. The electrical properties of GaN was investigated using transmission line model (TLM) structures, near and far from the mask edge. The sheet conductance was found to be greatly enhanced near the mask edge, related to enhanced n-type impurity incorporation during the non-c-plane growth in this region. The choice of mask material, SiO2 or AlN, was also shown to influence the sheet conductance.