Final polishing of Ga-polar GaN substrates using reactive ion etching

Reactive ion etching of {0001} oriented plate-like GaN single crystals has been investigated using SiCl4:Ar:SF6 chemistry. The reactive ion etching pr ocess is highly chemical. Large anisotropy of the etching rate and of the m orphology has been established on <000(1)over bar>N-polar and (0001) Ga-pol ar sides of the GaN crystals, with remarkably higher rate on the N-polar si de. Atomic force microscopy measurements have shown smooth surface and good polishing effect obtained on Ga-polar side, while N-polar surface exhibits an increased roughness of a factor of 10 after RIE.