CRYSTAL-STRUCTURE AND RAMAN-SCATTERING IN ZN1-XMGXSE ALLOYS

Zn1-xMgxSe alloys have been grown on (100) GaAs substrates by molecula r beam epitaxy. Their crystal structures are determined form x-ray dif fraction spectra and are found to be zinc blende, rocksalt, and their mixture for x<0.5, x=1, and x similar to 0.6, respectively. The Raman spectra are measured and show two-mode behavior for those alloys with zinc blende structure. The long-wavelength frequencies of ZnSe- and Mg Se-like optical phonons are determined and the results can be expresse d as linear functions of x. The first-order Raman spectra are observed for MgSe and Mg-rich Zn1-xMgxSe alloys with rocksalt structure. Those Raman spectra are attributed to the scattering from optical phonons a ctivated by disorders and impurities, and their line shapes represent the phonon density of states. (C) 1995 American Institute of Physics.