超短脉冲激光辐照硅膜的热弹性  

Thermoelasticity effect on Si film irradiated by ultra-short pulse laser

作　　者：郭春凤[1] 于继平[1] 王德飞[1] 齐文宗[1] 

机构地区：[1]四川大学电子信息学院,成都610064

出　　处：《强激光与粒子束》2008年第6期907-911,共5页High Power Laser and Particle Beams

摘　　要：考虑到热电子崩力的影响,在基于玻耳兹曼理论弛豫时间近似的非线性自相关模型基础上,将晶格温度与应变速率相耦合,建立了超短脉冲激光作用下半导体材料的超快热弹性模型。在单轴应变条件下,利用有限差分法模拟了500 fs脉冲激光作用下2μm厚硅膜内的载流子温度、晶格温度、载流子数密度、热应力和热电子崩力等的变化情况。结果表明:在低能量密度激光条件下,热弹性效应对半导体材料的影响很小;载流子温度达到峰值的时间比激光强度达到峰值的时间早,随后载流子数密度达到峰值,以及激光脉冲作用5 ps以后硅膜趋于总体热平衡;在脉冲辐照早期,非热平衡阶段形成的热电子崩力在超快损伤过程中起主要作用。An ultrafast thermoelasticity model for the thermomechanical behaviors in semiconductors irradiated by ultrashort pulse laser is presented based on the complete self-consistent model. It accounts for the coupling effect between lattice temperature and strain rate, as well as for the hot-electron-blast effect in momentum transfer. A finite difference method is developed for solving the coupled, nonlinear, transient differential equations under uniaxial strain condition. Numerical analysis is performed for a 2 μm silicon film heated by a 500 fs laser pulse to obtain the temporal and spatial evolution of the carrier temperature and density, the lattice temperature, the thermal stress and the hot-electron blast force. The results show that the ultrafast thermoelasticity effect has very little impact on semiconductors for low laser fluences. On the other hand, the major driving force for the damage is the so-called hot-electron blast force, which is generated by non-equilibrium hot electrons.

关 键 词：超短脉冲激光 硅膜 热弹性 热电子崩力 有限差分法 

分 类 号：TN215[电子电信—物理电子学] TP212[自动化与计算机技术—检测技术与自动化装置]