Phonon mode study of near-lattice-matched InxGa1−xAs using micro-Raman spectroscopy

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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 (0.42x<0.52).