Optical properties of native (anodic) layer on the InAlAs surface of different morphology

The influence of InAlAs/InP(001) heterostructures surface morphology on the optical properties (dispersive refractive index and extinction coefficient) of the anodic layer, formed by the oxidation in low-energy Townsend gas-discharge O2-Ar-containing plasma at room temperature, was studied using atomic force microscopy and ellipsometry methods. High resolution transmission electron microscopy and X-ray photoelectron spectroscopy were used to determine the anodic layer morphology and chemical composition. It is shown that the growth structural defects (pits) on the InAlAs surface, with a density 106–107 cm−2, do not significantly influence the optical properties of the amorphous anodic layers, mainly consisting of In2O3, Al2O3, As2O3 and elemental arsenic quite uniformly distributed over their depth and area. The thickness of thin (≤10 nm) oxide layers on InAlAs is measured at a high accuracy by the nondestructive ellipsometry method using the optical model of a single-layer isotropic film on an absorbing substrate.