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 ep itaxy grown (100)-oriented CdTe epilayers on both (100)GaAs and (100)Z nTe/GaAs. Ion channelling Rutherford backscattering spectrometry and c athodoluminescence (CL) measurements are used to study the effect of i nserting a proper ZnTe buffer layer [G. Leo et al., J. Vac. Sci. and T echnol. B 14 (1996) 1739] between CdTe and GaAs. The insertion of a Zn Te buffer layer improves the surface crystalline and optical quality o f the CdTe: CL images show that non-radiative recombination regions, a ssociated 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.