Organometallic vapor-phase epitaxial growth and characterization of the metastable alloy InP1−<i>x</i>Sb<i>x</i>

Abstract

The III-V metastable alloy InP1−x Sbx has been grown for the first time with compositions well inside the miscibility gap. Despite the large miscibility gap at the growth temperatures of 480–600 °C, epilayers with compositions covering the entire range from x=0 to 1.0 have been grown successfully by organometallic vapor-phase epitaxy at atmospheric pressure using the reactants trimethylindium, trimethylantimony, and phosphine. The 10-K energy band gap as a function of composition was determined from photoluminescence measurements combined with x-ray diffraction and electron microprobe analysis. The bowing parameter for the band-gap energy of the InP1−x Sbx was estimated to be 1.9±0.1 eV. The lattice dynamics have been studied using Raman spectroscopy in the frequency range from 150 to 400 cm−1. Long wavelength optical phonons display a ‘‘two-mode’’ behavior throughout the entire composition range. The InP-like longitudinal-optical and transverse-optical modes shift to lower frequency with increasing Sb concentration.