GAAS GROWTH MECHANISMS OF EXACT AND MISOR IENTED (001) FACES BY THE CHLORIDE METHOD IN H-2 - SURFACE-DIFFUSION, SPIRAL GROWTH, HCL AND GACL3 DESORPTION MECHANISMS

A general theoretical model of the {001}GaAs growth has been developed to understand the different processes involved in the AsCl3/H-2 and A sCl3/He systems. The step flow and spiral growth mechanisms, and the p rocesses of GaCl adsorption and chlorine desorption by H-2 in HCl have been determined by fitting theoretical and experimental curves. A mec hanism of GaCl adsorption in a second layer followed by GaCl3 desorpti on, determined from a fit to experimental results obtained in the AsCl 3/He system, explains the increase of the growth rate observed with H- 2 at low substrate temperature or at high GaCl molar fraction in the v apor phase. The parameters involved in the growth mechanisms have been calculated by taking into account mass transfert.