Effects of substrate temperature on the properties of In 0.48Ga 0.52P grown by molecular-beam epitaxy using a valved phosphorus cracker cell

Abstract

We report the molecular-beam epitaxial (MBE) growth of high-quality In 0.48Ga 0.52P epitaxial layers on GaAs substrate using a valved phosphorus cracker cell at a wide range of substrate temperature ( T s) from 440 to 520°C. Film characterization was carried out using double-axis X-ray diffraction (XRD), low-temperature photoluminescence (PL) and Hall-effect measurement. Typical InGaP layers showed a lattice mismatch of <10 −3 and PL full-width at half-maximum (FWHM) as low as 7 meV at 10 K, indicating materials with good structural and optical quality. The lattice mismatch remained relatively constant for samples grown between 440 and 500°C but increased significantly as the substrate temperature was increased to 520°C. Compositional measurements using XRD showed that indium desorption was significant in samples grown at substrate temperatures exceeding 500°C. The PL peak energy decreased from 2.014±0.008 to 1.968±0.008 eV as the substrate temperature was increased from 440 to 520°C. The highest PL peak energy of 2.014±0.008 eV which was indicative of the highest band gap was measured from the sample grown at T s=440°C. The results suggest that highly disordered (i.e. random) InGaP materials can be grown at low substrate temperature with excellent structural and optical quality.