Effects of mechanical polishing damage on the ir reflectance and attenuated total reflection spectra of n-type GaAs

Abstract

We have observed the effects of mechanical polishing with two different grit sizes on the infrared reflectance spectrum of high carrier density n-type GaAs. The two characteristic reflection minima observed with chemically etched and polished surfaces shift down in frequency and down in intensity as the grit size is increased from 0.3 to 1 μm. This behavior can be understood by assuming a damage layer in which the carrier density and mobility are decreased significantly. In addition, attenuated total reflection (ATR) spectra reveal the coupled surface plasmon–phonon modes associated with the bulk but shifted down due to the damage layer with optical constants different from those of the bulk.