X-ray reflectivity from ZnSe/GaAs heterostructures

ZnSe/GaAs heterostructures have been studied using x-ray reflectivity. Two samples grown by molecular beam epitaxy (MBE) differed in initial growing c onditions; the first was prepared by Se treatment of a GaAs substrate, and the second one was exposed to Zn before growth of the ZnSe film. The struct ure and morphology of the interface between the ZnSe film and GaAs substrat e were investigated. The experimental x-ray reflectivity curves, measured a t different wavelengths, were simulated using a distorted-wave Born approxi mation method. Fitting the experimental data indicated the presence of a Ga 2Se3 transition layer between the ZnSe film and GaAs substrate for the Se-t reated sample, confirming that Zn treatment during the MBE growing process improves the interface quality. Furthermore, the simulations indicated that the concentration of the Ga2Se3 was less than unity. From this, we propose that the transition layer is discontinuous, e.g., possesses an island-like morphology. (C) 1999 American Institute of Physics. [S0021-8979(99)08103-7 ].