Characterization of surface damage in dry-etched InP
Sn-doped InP wafers were etched by reactive ion beam etching (RIBE) using a gas mixture of at ion energies varying from 100 to 600 eV. We investigated the radiation damage caused by RIBE using various techniques which are sensitive to the near-surface region. The optical and electrical properties of the damaged layer as a function of ion energy were studied by photoluminescence microscopy (PLM), photoluminescence spectroscopy, spectroscopic ellipsometry (SE) and electrochemical capacitance - voltage profiling. The electron channelling pattern technique (ECP) was used to examine the structural disorder. The observed radiation damage was attributed to the formation of phosphorus vacancies indicating preferential loss of phosphorus in the InP. We found optimum etching conditions at an ion energy of 400 eV representing the best trade-off between high etch rate and low radiation damage. The potential of PLM, SE and ECP as fast and non-destructive techniques for quality control in research as well as manufacturing is demonstrated.