Raman scattering in Al<i>x</i>Ga1−<i>x</i>As<i>y</i>Sb1−<i>y</i> quaternary alloys

Abstract

The Raman scattering of AlGaAsSb quaternary alloy semiconductors has been investigated for the first time. The AlGaAsSb quaternary alloys, including the AlGaSb ternary alloys, were grown by organometallic vapor phase epitaxy. The dependence of the long-wavelength longitudinal-optical phonon frequencies on the composition are reported. The first-order Raman spectra show a two-mode behavior for the AlGaSb ternary alloys and a three-mode behavior for the AlGaAsSb quaternary alloys. For AlGaAsSb, two peaks located below 300 cm−1 are assigned as the GaAs- and GaSb-like LO modes. Two peaks observed above 300 cm−1 are assigned as the ‘‘AlAs plus AlSb’’ LO and TO modes. A broad peak observed below 200 cm−1 is assigned as a disorder-activated acoustic phonon mode.