Role of the initial growth mode on the dislocation structure in MBE grown ZnSe/GaAs(100)

Abstract

We investigate the effect of manipulating the initial growth mode of ZnSe on GaAs(100) on the dislocation distribution and crystal quality of the epilayers. The growth mode is manipulated, from a three-dimensional to a two-dimensional one, by controlling the impinging sequence of source beam fluxes on Ga or As stabilized GaAs(100) surfaces. Through electron microscopy, photoluminescence, and Raman spectroscopy studies we find that an increasingly two-dimensional growth mode strongly improves crystal quality, and results in drastic reduction of threading dislocation densities. Growth of a 1 μm ZnSe layer under two-dimensional initial growth conditions results in a very low (fewx10 6 cm -2) threading dislocation density at the epilayer surface.