Effect of controlled growth rate on the tilt mosaic microstructure of nonpolar a‐plane GaN grown on r‐plane sapphire

All the nonpolar a‐plane GaN epilayers were grown on nominally on‐axis r‐plane sapphire substrate in metalorganic chemical vapor deposition reactor. The growth rate of a‐plane GaN epilayers was controlled by TMGa flow rate, f[TMGa]. The GaN epilayer grown at high growth mode reveals striated morphology with triangular‐shaped pits with sharp corner, suggesting a relatively higher growth rate on the (11_00) m‐plane facet than (112_0) a‐plane facet. In case of low growth rate, the reason for high difference of ω tilt offset was considered by higher compressive uniaxial strain of m‐axis. Room temperature photoluminescence measurement revealed that the band‐edge emission intensity increased at high TMGa flow rate, which consider reduction in the nonradiative recombination centers.