Phonon mode study of near-lattice-matched In<i>x</i>Ga1−<i>x</i>As using micro-Raman spectroscopy

Abstract

We identify the four allowable phonon modes in InxGa1−xAs on InP:InAs-like transverse optical (TO) (225±2 cm−1), InAs-like longitudinal optical (LO) (233±1 cm−1), GaAs-like TO (255±2 cm−1), and GaAs-like LO (269±1 cm−1), using the selectivity of first-order Raman scattering off the (100) normal surface and the (011) cleaved plane and detailed line-shape analysis employing a sequential simplex optimization procedure. Raman scattering off the (011) cleaved plane was achieved for the first time in thin-film InGaAs using microprobing capabilities (∼1 μm). We also identify another phonon mode R* at 244 cm−1 which is attributed to an alloy disorder mode in these films. For the five identified phonon modes, a linear relationship between the Raman frequencies and composition determined from x-ray diffraction was determined for near-lattice-matched conditions (0.42&amp;lt;1−x&amp;lt;0.52).