SITU CHARACTERIZATION OF ZNSE GAAS(100) INTERFACES BY REFLECTANCE DIFFERENCE SPECTROSCOPY/

We discuss the structure and formation mechanism of ZnSe/GaAs(100) int erfaces as probed by reflectance difference spectroscopy (RDS). First we describe a simple analytic procedure that separates the surface and interface contributions in the RD spectra obtained for a heterostruct ure. The procedure opens up the new possibilities of RDS as an in situ interface probe. We have applied this technique to characterize the Z nSe/GaAs interfaces prepared on various GaAs(100) surfaces. The interf ace-anisotropy spectra thus obtained and the cross-sectional transmiss ion electron microscopy, show clearly that the chemical composition of the interfacial layer can be changed by controlling the reconstructio n and the pregrowth Zn and Se treatments of the initial GaAs surface. (C) 1996 American Vacuum Society.