Surface breakdown and nonlinear absorption in semiconductors exposed to pulsed CO2 laser radiation

Under the same conditions measurements were made of the threshold surface breakdown intensities of semiconductors having different band gaps (Ge, Те, InAs, InSb). The nonlinear absorption coefficients of InAs and InSb were determined. It was established that in spite of the appreciable differences between the densities of generated free carriers and in the induced absorption at prebreakdown intensities of the incident radiation, the surface breakdown thresholds of all four materials lie within a narrow range of intensities: (3–5)×10⁷ W/cm². On the basis of these results, it is concluded that prebreakdown generation of free carriers in the surface layer does not play a decisive role in the formation of breakdown.