Long-range order in CdxZn1-xTe epilayers grown on GaAs substrates

Abstract

Selected area electron diffraction pattern (SADP) and transmission electron microscopy (TEM) measurements were carried out to investigate the ordered structure in CdxZn1-xTe epitaxial layers grown on (001)GaAs substrates. The SADP showed two sets of superstructure reflections with symmetrical intensity, and the high-resolution TEM (HRTEM) image showed doublet periodicity in the contrast of the (111) lattice planes. The results of the SADP and HRTEM measurements showed that CuPt-type ordered structures with two different variants were observed in the CdxZn1-xTe epitaxial layers. The formation of a CuPt-type ordered structure in the CdxZn1-xTe epitaxial layer might originate from the minimization of strain relaxation energy in the reconstructed GaAs(001) surface. A possible atomic crystal structure for the CdxZn1-xTe epitaxial layer is presented based on the HRTEM results. These results provide important information on the microstructural properties for enhancing device efficiencies of operating at the blue-green region of the spectrum. (C) 2001 Elsevier Science B.V. All rights reserved.