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In-Situ Diagnostics of Plasma-Induced Damage on GaAs by Photoreflectance Spectroscopy
Published online by Cambridge University Press: 22 February 2011
Abstract
Photoreflectance spectroscopy (PR) is used to make in-situ diagnostics of subsurface damage behavior during Ar-plasma etching of n-type GaAs. The diagnostics in-situ PR first unveil anomalous damage behavior at an early stage of plasma etch- ing: Franz-Kerdysh oscillation shows an abrupt decrease in the surface electric-field strength from 130 to 30 kV/cm within 10 sec. This indicates that acceptor-like defects with a concentration of more than 1 × 1017cm−3 are created at the very beginning of the plasma etching. The δR/R abruptly decreased to 4% in intensity upon within 5 sec. of plasma etching and subsequently recovered. This indicates that recombination centers are quickly introduced, then further plasma etching gradually removes such centers, possibly by etching the damaged layer. Photoluminescence (PL) intensity decreases to 72% but does not show any recovery, indicating that PL is dominated by recombination centers in a deeper region. Thus, in-situ PR diagnostics is the first method to provide detailed findings on new damage behavior during Ar-lasma etching.
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- Copyright © Materials Research Society 1994
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