Elimination of rotational domain in ALN layers grown from GAAL FLUX and effects of growth temperature on the layers

We have been investigating crystal growth of AlN on nitrided sapphire substrates, and have grown c-axis oriented AlN layers using liquid phase epitaxy (LPE) with GaAl fluxes. However, rotational domains having 1-deg difference around the c-axis exist in the AlN layers. One of the purposes of this study is to eliminate the rotational domains. To do so, an annealing process at elevated temperatures was attempted before the LPE process. Then, its effectiveness was discussed. The origin of the rotational domain was explained using distortion of O ² ions arrangement in (0002) sapphire surface. The mechanism of the eliminating the domains was discussed using the lattice vibration of the sapphire at elevated temperatures. Secondly, effects of growth temperature on the AlN layers were investigated in terms of the growth rate, surface morphology and crystal quality. The growth rate of the LPE AlN layer increased concomitantly with increasing growth temperature at 13731673 K The growth rate attained at 1673K was 052 \μmh ¹ Crystal quality is almost independent of the growth temperature in that temperature range.