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
].