INSITU REFLECTANCE ANISOTROPY STUDIES OF THE GROWTH OF CDTE AND OTHER COMPOUNDS BY MOCVD

Using reflectance anisotropy (RA), we investigate in situ the metal-organic chemical vapor deposition (MOCVD) of CdTe and ZnTe on GaAs (100). RA transient signatures are observed at the beginning of the heteroepitaxy of lattice-mismatched semiconductors: CdTe on ZnTe and ZnTe on GaAs. RA records also exhibit a fast initial variation (deltar/r = 10(-3)) during the homoepitaxial growth of these II-VI compounds. In order to clearly understand those phenomena, surface coverage is analyzed by alternating the precursor flows. Large RA signals (deltar/r = 10(-2)) correlated with the 3D growth of ZnTe on GaAs are observed, before the material relaxation. These signals can be-interpreted in terms of surface roughness evolution within the framework of the effective medium theories (EMT). Moreover, ex situ spectroscopic measurements of CdTe layers are performed and simulated; a good agreement is obtained between EMT models and experiments.