Thermal damage of monocrystalline silicon irradiated by long pulse laser

In order to investigate thermal damage law and mechanism of monocrystalline silicon irradiated by millisecond pulsed laser, the temperature of monocrystalline silicon irradiated by millisecond pulsed laser was measured by high precision point temperature meter and spectral inversion system. Then the temperature evolution process was analyzed. Also, the temperature state during the whole process of thermal damage of monocrystalline silicon irradiated by millisecond pulsed laser and the corresponding damage structure were studied. The results of this study show that the peak temperature of laser-induced monocrystalline silicon increases with the increase of energy density when the pulse width is fixed. When the pulse width was between 1.5−3.0 ms, the temperature decreased with the increase of pulse width. Temperature rise curve showed inflection point when it was close to the melting point (1 687 K), the reflection coefficient was from 0.33 to 0.72. During the gasification and solidification stages, it also shows the gasification and the solidification plateau periods. Thermal cleavage damage of monocrystalline silicon precedes thermal erosion damage. Stress damage dominates under low energy density laser irradiation, while thermal damage dominates under high energy density laser irradiation. The damage depth was proportional to the energy density and increases rapidly with the increase of the number of pulses.