Significantly improved surface morphology of N-polar GaN film grown on SiC substrate by the optimization of V/III ratio

In this paper, N-polar GaN films with different VIII ratios were grown on vicinal C-face SiC substrates by metalorganic chemical vapor deposition. During the growth of N-polar GaN film, the VIII ratio was controlled by adjusting the molar flow rate of ammonia while keeping the trimethyl-gallium flow rate unchanged. The influence of the VIII ratio on the surface morphology of N-polar GaN film has been studied. We find that the surface root mean square roughness of N-polar GaN film over an area of 20 x 20 mu m(2) can be reduced from 8.13 to 2.78 nm by optimization of the VIII ratio. Then, using the same growth conditions, N-polar InGaN/GaN multiple quantum wells (MQWs) light-emitting diodes (LEDs) were grown on the rough and the smooth N-polar GaN templates, respectively. Compared with the LED grown on the rough N-polar GaN template, dramatically improved interface sharpness and luminescence uniformity of the InGaN/GaN MQWs are achieved for the LED grown on the smooth N-polar GaN template. Published by AIP Publishing.