Indium Composition Dependence of Raman Spectroscopy and Photocurrent of InxGa1−xAs Strained Layers Grown by Using MOCVD

Abstract

The photocurrent and Raman were studied for the InxGa1−xAs strained layers grown on GaAs (001) substrates by using metalorganic chemical vapor deposition (MOCVD) with different indium compositions. The indium composition in the InxGa1−xAs strained layers was determined by using high-resolution X-ray diffraction (HR-XRD) and Vegard’s rule. The in-plane lattice constants and tensile strains of the InxGa1−xAs strained layers were evaluated as functions of the indium composition. The tensile strain of the InxGa1−xAs strained layers increases as the indium composition increases. The Raman spectra are observed to be dominated by the GaAs longitudinal optical (LO) phonon mode as the strongest peaks show up around 287∼292 cm−1. Moreover, the weak and broad spectral features in the range of 265∼270 cm−1 originate from the peaks associated with the GaAs transverse optical (TO) phonon mode. The Raman peak also shifts toward lower wave number with increasing indium compositions, which indicates the presence of tensile strain in the InxGa1−xAs layers. As the indium composition increases, the band-gap shift decreases for temperatures ranging from 30 to 300 K.