长脉冲激光辐照单晶硅的热损伤

Thermal damage of monocrystalline silicon irradiated by long pulse laser

为探究毫秒脉冲激光辐照单晶硅的热损伤规律和机理,利用高精度点温仪和光谱反演系统对毫秒脉冲激光辐照单晶硅的温度进行测量。分析温度演化过程,研究毫秒脉冲激光对单晶硅热损伤全过程的温度状态和对应的损伤结构形态。研究表明:脉冲宽度固定时,激光诱导的单晶硅的峰值温度随能量密度的增加而增加;当脉冲宽度在1.5~3.0 ms之间时,温度随脉冲宽度的增加而降减小。温度上升曲线在熔点(1 687 K)附近时出现拐点,反射系数由0.33增加为0.72。在气化和凝固阶段,出现气化和固化平台期。单晶硅热致解理损伤先于热致熔蚀损伤,在低能量密度激光作用条件下,应力损伤占主导地位,而在大能量密度条件下,热损伤效应占主导地位。损伤深度与能量密度成正比,随脉冲个数增加迅速增加。

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 between1.5-3.0 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.