Intervalence-Band Absorption Saturation And Optically Induced Damage Of GaAs By Pulsed CO2 Laser Radiation

R. B. James; W. H. Christie; R. E. Eby; L. S. Darken Jr.; B. E. Mills

doi:10.1117/12.976149

20 November 1985 Intervalence-Band Absorption Saturation And Optically Induced Damage Of GaAs By Pulsed CO₂ Laser Radiation

R. B. James, W. H. Christie, R. E. Eby, L. S. Darken Jr., B. E. Mills

Author Affiliations +

Proceedings Volume 0540, Southwest Conf on Optics '85; (1985) https://doi.org/10.1117/12.976149
Event: 1985 Albuquerque Conferences on Optics, 1985, Albuquerque, United States

Abstract

The absorption of CO2, laser radiation in p-type GaAs is dominated by direct free-hole transitions between states in the heavy- and light-hole bands. For laser intensities on the order of 10 MW/cm2, the absorption associated with these transitions in moderately Zn-doped GaAs begins to saturate in a manner predicted by an inhomogeneously broadened two-level model. For heavily Zn-doped samples (>1018 cm -3), large areas of the surface are found to melt at comparable laser energy densities, in contrast to the lightly doped samples in which the damage initially occurs in small localized sites. As the energy density of the CO2 laser radiation is progressively increased, the surface topography of the samples shows signs of ripple patterns, high local stress, vaporization of material, and exfoliation of solid GaAs fragments. X-ray emission data taken on the laser-melted samples show that there is a loss of As, compared to Ga, from the surface during the high temperature cycling. Secondary ion mass spectrometry (SIMS) measurements are used to study the diffusion of oxygen from the native oxide and the incorporation of trapped oxygen in the near-surface region of the GaAs samples that have been melted by a CO2 laser pulse. We find that oxygen trapping does occur, and that the amount and depth of the oxygen signal depends on the laser energy density and number of laser shots.

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R. B. James, W. H. Christie, R. E. Eby, L. S. Darken Jr., and B. E. Mills "Intervalence-Band Absorption Saturation And Optically Induced Damage Of GaAs By Pulsed CO₂ Laser Radiation", Proc. SPIE 0540, Southwest Conf on Optics '85, (20 November 1985); https://doi.org/10.1117/12.976149

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