Lattice parameters and optical characterization of Cd1-xMgxSe alloys grownby vertical gradient freezing technique

Single crystals of Cd1-xMgxSe ternaries grown by the vertical gradient free zing technique are characterized by X-ray diffraction and electron probe mi croanalysis as well as wavelength-modulated reflectivity and photoluminesce nce to establish their basic structural and optical properties. In the comp osition range 0 < x < 0.40, the alloys crystallize in the wurtzite structur e with lattice parameters decreasing linearly with increasing Mg concentrat ion (x). X-ray data considered in the context of interatomic distances yiel d an improved estimate of the tetrahedral covalent radius of Mg. Energy gap as a function of x increases linearly with increasing Mg concentration. Th e lattice parameters and the energy gap of the end member of the Cd1-xMgxSe wurtzite ternaries, i.e., of MgSe with the wurtzite structure, are deduced from those measurements. (C) 1999 Elsevier Science B.V. All rights reserve d.