POWDER DLFFR$CTION STUDY OF Zn&4g$e ALLOYS

Znl_xMg$e crystals were grown in the range extending up to x’ = 0.615 and characterized using the X-ray diffraction and electron probe microanalysis. Below x=0.2 there is a phase transition from sphalerite to wurtzite. The lattice constants are found to exhibit linear dependence on x for both, the sphalerite and wurtzite structure types. For compositions close to the phase transition, the formation of 4H and 8H polytypes as main or secondary phases is observed. The energy gap in the investigated composition range is higher than that reported for thin Znr_,M&Se layers on GaAs substrate.