Optical and Electrical Characterisation of Plasma Processed N-GaAs

Abstract

AbstractA Photoreflectance (PR), Photoluminescence (PL), Raman scattering and Ellipsometry optical characterisation study of He and SiCl4 reactive ion etched 1018cm−3 n-type GaAs is presented. Ellipsometric and PL data reveal significant modifications to the GaAs substrates for the He plasma as a function of etch power and etch gas pressure. Raman data reveal an increase in the depletion depth while the surface electric field data, extracted from PR spectra, decrease with etch severity. This is accounted for by a plasma etch induced decrease in the near surface net carrier density. Ellipsometric and PL measurements of SiCl4 etching reveal evidence of an improvement in the GaAs surface crystallinity while PR and Raman data are consistent with an increase in the surface carrier concentration. Optical characterisation data are correlated with electrical measurements using capacitance-voltage profiling.