Be-Se double-phonon behavior in Zn1-x-yMgyBexSe alloy

The longitudinal optical (LO) and transverse optical (TO) phonons of zincblende Zn1-x-yMgyBexSe with x,ysimilar to0.15 are identified by Raman scattering. The Be-Se region exhibits a two-mode behavior similar to that observed with the random Zn1-xBex(Se,Te) systems. This indicates that the percolation picture set for the latter mixed crystals with contrasted bond stiffness extends to Be-based multinaries. Accordingly the low- and high-frequency modes refer to Be-Se bonds within the Be-rich hard-like region and the (Zn,Mg)-rich soft-like one, respectively. Besides, we derive the (x,y) values together with the fraction p of Be atoms in the hard-like region from combined contour modeling of the TO and LO Raman line shapes. We find psimilar tox, as in the ZnBe(Se,Te) references. We deduce that the Be incorporation is random in ZnMgBeSe. (C) 2004 American Institute of Physics.