抄録
Inter-surface diffusion in GaAs MBE on (111)-(001) and (111) B-(001) non-planar substrates was studied by μ-RHEED/SEM MBE. A local growth rate on the (001) surface was measured as a function of distance from a boundary between (111) and (001) surfaces employing the technique developed by Hata et al,. It was found that the diffusion length of Ga incorporation at the growth steps depends strongly on the arsenic pressure. On (111) A-(001) non-planar substrate, Ga diffuses always from (111) A to (001) surhces in the range of arsenic pressure employed in this experiment. On the other hand, the direction of Ga diffusion was changed on (111) B-(001) non-planar substrate depending on the arsenic pressure. When the arsenic pressure was high, Ga diffuses from (001) to (111) B surfaces while when it was low the direction of the diffusion was reversed. By solving the diffusion equation, an equation for the local growth rate was derived and the diffusion lengths on the (111) A and (111) B surfaces were calculated. It was found that the change of diffusion flow on (111) B-(001) surfaces is due to the different arsenic pressure dependence of Ga lifetime on (111) B and (001) surfaces. The reason for the long diffusion length as long as 1μm on non-planar substrate was discussed and it is suggested that the larger Ga surface flux than that of As_4 makes the incorporation efficiency of Ga at the step edge considerably low.
