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 degrees C. The coalescence of these GaN islands yields a reduction of the total number of extended defects from the 10(10)-10(11) cm(-2) range usually obtained down to the low 10(9) cm(-2) range for the best samples. (C) 1998 American Institute of Physics. [S0003-6951(98)04535-5].