The influence of various MOCVD parameters on the growth of Al1−xInxN ternary alloy on GaN templates

We have studied the growth of AlInN lattice matched to GaN. We present the effect of reactor pressures, ammonia flux, total nitrogen gas flow, and the presence of hydrogen on the growth of Al-rich Al1−xInxN epilayers (x<0.2) on GaN templates on (0 0 0 1) sapphires by MOCVD. The reactor pressure is found to be a critical parameter not only for the surface morphology but also for indium incorporation. Our experimental result ascertains that the main controlling factor associated with the pressure is the chemical parasitic reaction. With an increase in NH3 flux from 2.5 to 5 slm, the surface roughness has substantially improved from 8.3 to 2.3 nm and the V-pit density has reduced from 7.2×108 to 3.2×108 cm−2. This significant improvement is ascribed to the enhanced lateral growth rate induced by the raised V/III ratio. The effects of hydrogen with different flow rates during the growth of ∼200 nm-thick Al1−xInxN epilayers have been investigated with respect to the surface morphology, bulk crystalline quality, indium incorporation and strain relaxation.