GaAs Oxide Removal Using Hydrogen Plasma Studied by Surface Second-Harmonic Generation

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Abstract
Surface-reflection second-harmonic generation (SHG) was applied to observe the surface-oxide removal of GaAs(001) using a pulsed hydrogen plasma. Real-time observations were carried out to monitor a specific polarization component of SHG. The p-polarized SH intensity under p-polarized excitation increased in the [01̄1] azimuth of incidence and decreased in the [011] azimuth of incidence during hydrogen plasma irradiation while the other component, the p-polarized SH intensity under s-polarized excitation did not change. The input polarization-angle dependence was examined before and after the oxide removal. The variation in the SH intensity during the hydrogen plasma treatment was found to be mainly due to variation in the surface-susceptibility tensor elements. Among these, an “isotropic” tensor element, ∂ z z z (or ∂ξξz =∂ηηz ), changes most significantly.