QUANTITATIVE CHEMICAL DEPTH PROFILES OF ANODIC OXIDE ON GAAS OBTAINED BY X-RAY PHOTOELECTRON-SPECTROSCOPY

The composition and structure of anodic oxides about 400A thick grown in either 3% tartaric acid/propylene glycol or KaCO7/HOCH2 · CH2OH electrolytes are investigated. The ion sputtering ettects are taken into account to obtain quantitative chemical depth profiles. The K2Cr2O7-grown oxide is in-homogeneous with an average Ga3+/(oxidized As) ratio of ~3 and ~1 in the surface region and the bulk of this oxide, respectively, while the tartaric acid-grown oxide is homogeneous with a Ga3+/As3+ ratio of ~1 throughout the oxide film except in the interfacial region. In the outer layer (~100A) of the K2Cr2O7-grown oxide, a large quantity of oxygen exists and the arsenic oxide is not AS2O3 but AS2O5. In both ~400A thick anodic oxide/GaAs interfacial regions, whose width is ~100å, excess As exists and its quantity is approximately equal to the concentration difference between Ga2O3 and AS2O3 in this region. © 1979, The Electrochemical Society, Inc. All rights reserved.