UC Santa Barbara

We demonstrate a technique to reduce the extended defect densities in a-plane GaN deposited on r-plane sapphire. The SiO2 lateral epitaxial overgrowth mask consisted of (GaN) stripes. Both the mask and GaN were etched through the mask openings and the lateral growth was initiated from the etched c-plane GaN sidewalls, and the material was grown over the mask regions until a smooth coalesced film was achieved. Threading dislocation densities in the range of 10(6)-10(7) cm(-2) were realized throughout the film surface. The on-axis and off-axis full width at half maximum value and surface roughness were 0.082 degrees, 0.114 degrees, and 0.622 nm, respectively. (c) 2006 American Institute of Physics.