Temperature-dependent measurements on ZnSe heterostructures by high-resolution X-ray diffraction

Thermally induced strain in ZnSe epitaxial layers on GaAs occurs due to the different expansion coefficients of the single materials. This strain is directly investigated by high-resolution X-ray diffraction in the temperature range from 10 to 600 K. The strain is measured for a thick relaxed and a thin pseudomorphic layer. Furthermore, the lattice constants of ZnSe and GaAs bulk materials are determined at variable temperatures. It was observed that the thermal expansion is quite linear for GaAs and ZnSe only in the temperature range from 250 to 600 K. The measured temperature-dependent lattice constants and the derived expansion coefficients are input parameters for a model to calculate the thermally induced strain in the epitaxial layers. Good agreement could be obtained between the experimental data and the model. (C) 1998 Elsevier Science B.V. All rights reserved.