Surface and Interface Damage Characterization of Reactive Ion Etched MBE Regrown GaAs

Abstract

AbstractDamage resulting from reactive ion etching (RIE) and wet etching of MBE grown GaAs and the defects generated in subsequent GaAs regrowth was evaluated by Transmission Electron Microscopy (TEM), photoluminescence (PL) , and Raman spectroscopy. The samples were reactively etched with HCl and Cl2 at two power densities; 0.3 W/cm2 and 0.6 W/cm2. A wet chemical (H2O:H3PO4:H2O2) etched sample was used for comparison. The LO phonon intensities measured by room temperature Raman spectroscopy showed a strong correlation to the relative PL intensities, where the HCl sample was found to be inferior to the others. TEM microstructural evaluation showed both HCl RIE samples to have significant interface roughness, with the sample etched at 0.6 W/cm2 showing the most structural damage in the regrowth region. Defect densities for the Cl2. and wet etched samples were two orders of magnitude lower than that of the HCl etched samples. The extent of disorder in the regrowth region was largest for the HCl sample with respect to the Cl2 and wet etched samples. These microstructural and optical results suggest that the H+ ion plays an important role in the generation of crystal defects during the RIE process.