X-Ray Diffraction of CdTe Epitaxial Layers on GaAs Substrates as a Function of Temperature

Abstract

X -ray diffraction of CdTe epitaxial layers on GaAs substrates as a function of temperatureR. D. Horning, J. -L. Staudenmann, U. Bonse,* D. K. Arch, ** and J. L. Schmit **Ames Laboratory -USDOE and Department of PhysicsIowa State University, Ames, Iowa 50011AbstractA (0,0,1) epitaxial layer of CdTe on a (0,0,1) GaAs substrate has been studied as afunction of temperature by x -ray diffraction. Lattice parameters and integratedintensities of Bragg reflections were measured between 10 K and 360 K using a wavelength of0.7093 A (Mo Ka). The lattice parameters were measured parallel and perpendicular to theinterface. The changes of the integrated intensities with temperature give informationabout the thermal vibrations. Average Debye temperatures for the substrate and epilayerare 232 ±2 K and 142 ±2 K, respectively. These data are compared with data from CdTe andGaAs single crystals in order to understand how strain is propagated and /or relieved in thecomposite system.IntroductionThe epitaxial growth of CdTe on GaAs substrates has been reported by a number of groupsusing a variety of growth methods.' This composite system represents an extreme case ofepitaxy; the lattice mismatch between CdTe and GaAs is 14.7% with respect to GaAs.