光学学报, 2009, 29 (3): 752, 网络出版: 2009-03-17
绝缘衬底上硅表面载流子的超快动力学研究
Ultrafast Carrier Dynamics in Surface of Silicon-on-Insulator
摘要
利用800 nm波长的飞秒抽运探测技术测量了具有不同单晶硅薄膜厚度的绝缘衬底上硅(SOI)皮秒瞬态反射率变化,并通过基于受激载流子密度和温度变化过程建立的反射率模型讨论了SOI表面载流子的超快动力学过程。研究表明,表面复合速度(SRV)是影响载流子动力学响应的主要因素,且薄膜厚度越小表面复合速度就越大,对应的表面态密度可达到1015 cm-2。对于较小的SRV,受激载流子的超快响应决定了瞬态反射率变化; 而对于较大的SRV,晶格温升对瞬态反射率变化的贡献变得显著,使得反射率在更短的时间内恢复并超过初始值。
Abstract
Time-resolved reflectivity changes of silicon-on-insulator (SOI) with different crystalline silicon film thicknesses have been measured using the femtosecond (λ=800 nm) pump-probe technique to investigate the ultrafast carrier dynamics. The underlying physics of carrier diffusion and recombination processes is discussed using the reflectivity model, which is based on the time evolution of photoexcited carrier density and temperature. The research shows that, the contribution of surface recombination velocity (SRV) dominates the response of excited carrier dynamics, and the SRV increases with thickness of silicon thin films decreasing. The corresponding active surface state density can reach 1015 cm-2. For relatively small SRV, the transient reflectivity changes are dominated by the ultrafast response of photoexcited carriers. But the contribution of lattice temperature appears to be more significant with large SRVs, which causes the reflectivity to recover and surpass the initial value in shorter time.
刘国栋, 王贵兵, 李剑峰, 付博, 罗福. 绝缘衬底上硅表面载流子的超快动力学研究[J]. 光学学报, 2009, 29(3): 752. Liu Guodong, Wang Guibing, Li Jianfeng, Fu Bo, Luo Fu. Ultrafast Carrier Dynamics in Surface of Silicon-on-Insulator[J]. Acta Optica Sinica, 2009, 29(3): 752.