START OF MISFIT RELAXATION IN GAAS-ZNSE HETEROSTRUCTURES

The start of relaxation of ZnSe epitaxial layers grown on GaAs(0 0 1) substrates by the formation of dislocations will be discussed in this article. The minimum dislocation density, which is detectable with hig h-resolution X-ray diffraction omega - 2 Theta scans, is limited by th e minimum measurable parallel lattice misfit. According to this criter ion nearly all of the ZnSe layers measured in this study are totally s trained. The accuracy of the X-ray measurements can be increased by th e use of reciprocal space maps. The reciprocal space maps prove the ex istence of a linear dislocation array along the [1(1) over bar0$]-dire ction. The influence of different substrates, doping, the GaAs-ZnSe in terface preparation and the ZnSe layer thickness on the number of defe cts will discussed. (C) 1998 Elsevier Science B.V. All rights reserved .