A theoretical treatment of GaAs growth by vapour phase transport for {001} orientation

The normal growth rate of a {001} face has been theoretically studied; by considering either direct fixation of gallium arsenide molecules, or formation of intermediate surface compounds. From the theory of rate processes, it appears that experimental results can be interpreted by considering the reactions of desorption of the chlorine atoms adsorbed on surface as limiting the growth. A theoretical expression of the normal growth rate based on desorption by hydrogen has been performed. The descending portions of the curves with decreasing substrate temperature or increasing partial pressure of gallium monochloride, appear as due to an increasing coverage of surface with gallium monochloride molecules. Absolute theoretical values agree with experimental published measures, except for the weakest substrate temperatures. This disagreement may be due to the possibility of desorption of two chlorine atoms by gallium monochloride and formation of gallium trichloride molecules.