Gallium surface diffusion on GaAs (001) surfaces measured by crystallization dynamics of Ga droplets

摘要

We present accurate measurements of Ga cation surface diffusion on GaAs surfaces. The measurement method relies on atomic force microscopy measurement of the morphology of nano-disks that evolve, under group Ⅴ supply, from nanoscale group Ⅲ droplets, earlier deposited on the substrate surface. The dependence of the radius of such nano-droplets on crystallization conditions gives direct access to Ga diffusion length. We found an activation energy for Ga on GaAs(001) diffusion E_A=1.31±0.15 eV, a diffusivity prefactor of D_0 = 0.53(×2.1±1) cm~2 s~(-1) that we compare with the values present in literature. The obtained results permit to better understand the fundamental physics governing the motion of group Ⅲ ad-atoms on Ⅲ-Ⅴ crystal surfaces and the fabrication of designable nanostructures.