Effects of growth conditions on AlN layer grown by Ga-Al liquid phase epitaxy

We developed an original liquid phase epitaxy technique that uses Ga-Al solution to grow AlN on surface nitrided sapphire substrates. In this paper, effects of temperature, solution composition, and N2 gas flow rate on the growth of AlN layer were investigated. The AlN layer grown in the solution with higher Al content and higher growth temperature tended to dissolve into the solution, thus, the AlN layers exhibited inhomogeneous surface. The growth rate had a maximum at 60 mol%Al and at 1673 K for solution composition dependence and growth temperature dependence, respectively. On the other hand, the growth rate monotonically increased with increasing N2 gas flow rate. Based on these results, growth mechanism and rate-determined step of this liquid phase epitaxy process were discussed.