Structural analysis of HgCdTe and PbSnTe native oxide films

Abstract

The aim of this work is to determine the structure of native oxides of HgCdTe and PbSnTe grown by different methods. The starting materials were epitaxial layers HgCdTe and PbSnTe. Anodic oxides were fabricated under standard conditions, and chemical oxides were grown in H2O2-KOH solution. The oxide films have been studied by reflection high-energy electron diffraction (RHEED). Only oxides obtained through natural oxidation in ambient air at room temperature were found to be completely amorphous. All other oxides must be rated as polycrystalline, and their average size of crystallites was determined using Scherrer's formula. To determine the main oxide components, interplane distances were measured on electron diffraction patterns. CdTeO3 and PbTeO3 may be considered such components in HgCdTe and PbTe anodic oxides correspondingly that is well agreed with predictions based on the phase equilibria in Hg(Pb)-Cd(Sn)-Te-O systems as well as XPS and AES results previously obtained. For PbTe chemical oxide, the presence of TeO2 was detected and it is supposed that the chemical oxidation involves the bimodal oxidation, whereby Pb and Te components in PbTe oxidize separately. By using the microindentation technique the microhardness in the semiconductor layer underlying oxides was investigated, it was determined that for HgCdTe anodic oxide, the microhardness is always increased while for PbTe, both anodic and chemical oxidation decreases the microhardness. Copyright © 2008 John Wiley & Sons, Ltd.