Structural study of (100) CdTe epilayers grown by MOVPE on ZnTe buffered and unbuffered (100) GaAs

We report on the structural assessment of metalorganic vapour phase epitaxy grown (100)-oriented CdTe epilayers on both (100)GaAs and (100)ZnTe/GaAs. Ion channelling Rutherford backscattering spectrometry and cathodoluminescence (CL) measurements are used to study the efl'ect of inserting a proper ZnTe buffer layer [G. Leo et al., J. Vac. Sci. and Technol. B 14 (1996) 1739] between CdTe and GaAs. The insertion of a ZnTe buffer layer improves the surface crystalline and optical quality of the CdTe: CL images show that non-radiative recombination regions, associated with extended defects, strongly decrease when a ZnTe buffer layer is used. Also, enhanced excitonic emissions are observed in the case of CdTe/ZnTe/GaAs samples.