The dielectric functions of InP, In0.53Ga0.47As, and In0.75Ga0.25As0.5P0.5 epitaxial layers have been measured using a polarization-modulation spectroscopic ellipsometer in the 1.5 to 5.3 eV region. The oxide removal procedure has been carefully checked by comparing spectroscopic ellipsometry and x-ray photoelectron spectroscopy measurements. These reference data have been used to investigate the structural nature of metalorganic chemical-vapor deposition grown In0.53Ga0.47As/InP and In0.75Ga 0.25As0.5P0.5/InP heterojunctions, currently used for photodiodes and laser diodes. The sharpness of the interfaces has been systematically compared for the two types of heterojunctions: In 1-xGaxAsy/InP and InP/In 1-xGaxAsyP1-y. The sharpest interface is obtained for InP growth on In0.75Ga 0.25As0.5P0.5 where the interface region is estimated to be (10±10) Å thick. The importance of performing in situ SE measurements is emphasized.
ASJC Scopus subject areas
- Physics and Astronomy(all)