Low Temperature Growth Mechanism of GaN Crystal by Hydride Vapor Phase Epitaxy

The low temperature growth of GaN crystal using epitaxy lateral overgrowth (ELO) on SiO₂ dot pattern below 900°C by hydride vapor phase epitaxy (HVPE) have been studied. It is observed that the growth rate of GaN hexagonal pyramidal crystals along [11̄01] direction increases as growth temperature decreases. At low temperature of ∼ 850°C, hexagonal GaN columnar crystals with high index facet at the top can be observed. It is proposed that the surface diffusion length of precursors, such as NH ₃ and GaCl, decreases at lower temperature that reduces the probability of desorption and increase the lifetime. The condensation of Ga liquid droplets on the GaN surface will change the relative stability of {11̄01} facet. Therefore, the formation of high index planes such as {112̄2} facet on the top of hexagonal column along with the formation of stacking fault on the (0001) plane can be observed. A detailed study of the effect of growth temperature on the crystal growth mechanism will be presented.