PLASMA-LONGITUDINAL OPTICAL PHONON COUPLED MODES IN ZN1-XMGXSYSE1-Y GAAS HETEROSTRUCTURES/

Photoluminescence (PL) and Raman scattering measurements on undoped an d doped Zn1-xMgxSySe1-y epitaxial films grown on GaAs (1 0 0) substrat es by molecular beam epitaxy (MBE) were performed to investigate the o ptical and the lattice dynamical properties of Zn1-xMgxSySe1-y epilaye rs. PL measurements in the temperature range between 11 and 260 K show that the peaks related to the donor-to-acceptor pair and the free ele ctron-to-acceptor transitions in N-doped Zn1-xMgxSySe1-y epilayers are much broader than those in N-doped ZnSe. Raman scattering measurement s show plasma-longitudinal optical phonon (PLOP) coupled phonon modes, as well as the three longitudinal optical phonon mode behavior of the Zn1-xMgxSySe1-y lattice vibrations. Power-dependent Raman spectra sho w that the higher branch of the PLOP coupled mode shifts to lower freq uency with decreasing power density. The appearance, of the PLOP mode indicates that the Zn1-xMgxSySe1-y epilayers grown on the GaAs substra tes by MBE have very high-quality interfaces and that they hold promis e for potential applications as cladding layers for laser diodes and r elated optoelectronic devices operating in the blue to ultra-violet re gion. (C) 1998 Elsevier Science Ltd. All rights reserved.