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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。
The transient reflectivity of single-crystal silicon surface was measured by using the femtosecond pump detection technology at 800 nm. The ultrafast dynamics of surface charge carriers were investigated. The reflectivity model based on the change of free carrier density can well describe the change of transient reflectivity, indicating that the contribution of the fast response of stimulated free carriers dominates the change of reflectivity, and the sample The surface recombination velocity (SRV) was 1.2 × 10 6 cm / s. A coupled carrier transport model was established to investigate the evolution of the density and temperature of hot carriers on the surface of monocrystalline silicon with time. The research shows that the surface recombination process is an important factor that affects the carrier mobility of the intrinsic silicon surface.