Structural properties of ZnSe films grown by migration enhanced epitaxy

Abstract

We describe the structural properties of ZnSe grown on (001) GaAs by migration enhanced epitaxy, and show that the heterointerface plays a significant role in determining the structural properties of the ZnSe films. Films were grown with thicknesses ranging from 900 to 10 000 Å. Transmission electron microscopy and high-resolution x-ray diffraction measurements show that the resulting structure is highly dependent on how growth is initiated. Nearly perfect films are obtained, for thicknesses up to about 2500 Å [considerably thicker than the critical thickness for molecular beam epitaxy (MBE)-grown films], when growth begins with an initial exposure of the GaAs substrate to Zn. However, if growth begins with an initial high-temperature Se exposure, then stacking fault densities are greatly increased, and more rapid relaxation occurs. Comparison to MBE-grown films shows greater defect densities and a faster rate of relaxation of the misfit strain for the MBE-grown films.