Laser-induced free-carrier absorption in Si single crystal

The transmitted energy density in thin single Si crystal, wafers is measured atλ=1.06 μm as a function of the incident energy density for a Nd laser pulse of 30 ns duration. Non-linear effects begin to become important at about 0.3 J/cm2. The contribution due to free-carriers is separated from the interband one by using measurements made at low energy density and at different sample temperatures in the 20°–150 °C range. The time dependence of the free-carrier concentration and of the lattice temperature is computed for different values of the Auger constant. The experimental data in the 0.2–2.5 J/cm2 energy density range are fitted with an Auger constant of 10−30 cm6s−1.