MBE成長における核形成とステップカイネティックス(<特集2>原子レベルでの結晶成長)

概要

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Nucleation and growth kinetics in MBE are discussed taking GaAs as an example. Firstly, a surface diffusion equation was solved to obtaine theoretically the surface distribution of adatom concentration, the surface flux entering the growth step and the supersaturation ratio at the step edge. Then, for obtaining the surface diffusion length of Ga on GaAs (100) and (111) B surfaces the theory was applied to an experiment in which the critical temperature of the transition between a 2D-nucleation and a step flow modes was measured on the vicinal substrate. This analysis gave the diffusion length of Ga being 100-1000Å for 530-670℃. Finally, the supersaturation of Ga and In at the step edge were determined respectively for MBE growth of GaAs and (Ga, In) As. Theoretical analysis shows that the supersaturation of Ga at the GaAs step edge is less than 20% above 640℃ and that of In is 10-40% above 560℃. It is concluded that even in MBE, an equilibrium or near equilibrium is established in the growth reaction at the step edge at relatively high growth temperature.
日本結晶成長学会の論文
1992-03-15