In situ reflectance anisotropy studies of the growth of CdTe and other compounds by MOCVD

Abstract

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 ( δ/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 ( δ/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.