Gas-Phase Nucleation in GaAs Thin Film Preparation by Metal Organic Chemical Vapor Deposition

GaAs epitaxial film growth in the metal organic chemical vapor deposition (MOCVD) horizontal reactor was analyzed by a mathematical model, which takes into consideration of vapor phase hydrodynamic and kinetic phenomena including decomposition reactions of reactants, Ga or GaAs nucleation and subsequent particle growth. The position dependent changes in mass concentrations of Ga or GaAs monomers and homogeneously nucleated Ga or GaAs particles are predicted under various substrate temperatures. The appearance of particles in the gas phase is found to be enhanced under substrate temperature exceeding about 900 K. The conditions under which the growth of the thin film is governed by the diffusive deposition of metal organic vapor and Ga monomers are determined, and the effect of homogeneously nucleated particles on the growth of thin film has been clarified. The simulation results are in good agreement with the data of van de Ven et al [J. Cryst. Growth 76 (1986) 352].