超短脉冲激光对硅膜的热力效应分析

为了研究超短脉冲激光辐照下半导体材料的热力效应,在热电子崩力和自洽场两种模型的基础上,得到了完全耦合的非线性热弹方程组。在单轴应力条件下,采用有限差分法,讨论了不同脉宽的超短脉冲激光辐照下,硅膜内载流子温度、晶格温度、热应力以及热电子崩力随时间及膜深度的变化情况。结果表明,脉冲宽度对硅膜的热力损伤过程起重要作用。能量密度一定时,载流子和晶格达到热平衡所需时间随脉冲宽度的增加而增加;热电子崩力呈现明显的双峰结构,同时脉冲宽度对第二个峰值的影响较大;脉宽越窄,热应力的峰值越大,越容易对材料造成损伤,为激光加工和光电器件的损伤提供了理论参考。

Thermal-Mechanical Effect Analysis of Silicon Materials Heated by Ultrashort Laser Pulse

To research thermal-mechanical effect of semiconductors subjected to ultrashort laser heating, a set of fully cou pied thermoelasticity equations is derived based on the hot-electron blast and complete self-consistent models. With the assumption of uniaxial stress, numerical analysis is performed for a thin silicon film heated by different laser pulses using a finite difference method. The results, including the carrier and lattice temperature, hot-electron blast force and thermal stress, indicate pulse width plays an important role in the damage of silicon film. With the same value of the laser energy , the time which the carrier and lattice need to establish the thermal equilibrium is longer with the pulse increasing. The pulse width has a great influence on the second peak value of the hot-electron blast force which has a two-peak structure. The nar rower the pulse is, the greater the peak value of thermal stress is, and the damage to materials is more easy, which provides a theoretical reference for laser processing and the damage of optoelectronics.