The effect of the Si/N treatment of a nitridated sapphire surface on the growth mode of GaN in low-pressure metalorganic vapor phase epitaxy

In this letter, we studied the effect of the high-temperature Si/N treatment of the nitridated sapphire surface followed by the deposition of a low-temperature GaN nucleation layer on the growth mode of GaN in low-pressure metalorganic vapor phase epitaxy. It was shown that the nucleation layer, initially flat and continuous, converts to wide isolated truncated hexagonal islands having {1–101} facet planes and a top (0001) plane, after heating up to 1150 °C. The coalescence of these GaN islands yields a reduction of the total number of extended defects from the 1010–1011 cm−2 range usually obtained down to the low 109 cm−2 range for the best samples.