The surface treatment of sapphire substrate and its effects on the initial stage of GaN growth by MOVPE

摘要

The relationships among the pretreatment of sapphire substrate by dipping into hydrofluoric acid, the subsequent hydrogen annealing and the growth mode of GaN by MOVPE were investigated. An annealing temperature higher than 900 ℃ is necessary to remove fluorine atoms from a sapphire surface. The presence of fluorine atoms on the sapphire surface prohibits c-axis-oriented growth of GaN.