EQUILIBRIUM ADSORPTION AND SOME INTERFACIAL GROWTH PROCESSES IN GASEOUS SOLUTIONS AND CVD SYSTEMS(<Special Issue>Fundamentals of Vapour Growth and Epitaxy : Lecture Notes of the ICVGE-4 Specialists' School)

抄録

General relationships for adsorption of species in gaseous solutions are presented. The contribution of the adsorption layer/step flux to the growth rate is compared with the contribution of the direct gas/step flux. The adsorption of Cl, H, GaCl, As, As_2, As_4, Ga and AsGaCl species on GaAs (111)Ga and GaAs (111)AS have been considered. The results of an analogous consideration for Si(111) are presented. For Si(111) and GaAs (111)Ga the amount of vacant adsorption sites is = 1-10%, whereas for GaAs (111)AS it reaches =50%, depending on the gas phase composition and temperature. Surface diffusion is seriously hindered on the faces covered with the dense adsorption layers, the diffusion length going down to several tens of interatomic distances. Thus the possibility of an adlayer - gas-phase reaction is expected to play a considerable role. In the Ga-As-H-Cl system the GaCl and As_4 molecules turn out to be the major Ga- and As- containing species adsorbed on the (111) faces.