单晶硅表面载流子动力学的超快抽运探测

利用800 nm波长的飞秒抽运探测技术测量了单晶硅表面50 ps内的瞬态反射率变化,研究了表面载流子的超快动力学过程.基于自由载流子密度变化过程建立的反射率模型可以很好地描述瞬态反射率变化,说明受激自由载流子超快响应的贡献主导了反射率的变化过程.经拟合获得了样品的表面复合速度(SRV)为1.2×106cm/s.建立了耦合的载流子输运模型,探讨了单晶硅表面热载流子的密度、温度随时间的演化过程.研究表明,表面复合过程是影响本征单晶硅表面载流子动力学的重要因素.

Ultrafast Pump-Probe Reflectivity Study of Carrier Dynamics in Silicon Surface

Time-resolved reflectivity changes of crystalline silicon surface on a 50-ps time scale have been measured using the femtosecond (λ=800 nm) pump-probe technique, and the ultrafast carrier dynamics are also investigated. Time-resolved reflectivity changes can be well described by the reflectivity model which is based on the time evolution of free carrier density. This implies that the ultrafast response of reflectivity is dominated by the excited free-carrier contribution. Then the surface recombination velocity (SRV) value S=1.2×106 cm/s is extracted. A self-consistent carrier transport model is established to simulate the time evolution of carrier density and temperature. The results show that surface recombination plays a critical role in the response of carrier dynamics in intrinsic crystalline silicon surface.