光泵浦太赫兹探测对于不同掺杂硅的光激发动力学表征

Characterization of Photo-Excited Dynamics for Different Doped Si by Optical Pump Terahertz Probe

摘要:

提出了一种光泵浦太赫兹探测技术的改进方案,使用双色飞秒激光场电离空气诱导等离子体辐射的超短宽带太赫兹脉冲作为探测脉冲,表征了硅的光激发动力学,通过表征过程验证了基于所提改进方案的光泵浦太赫兹探测系统的性能。硅的泵浦深度随泵浦功率的增加而提高,400nm泵浦光的泵浦深度大于800nm泵浦光。使用400nm泵浦光,p掺杂硅的泵浦深度最大,本征硅次之,n掺杂硅最小；而使用800nm泵浦光,p掺杂硅的泵浦深度最大,n掺杂硅次之,本征硅最小。此外,基于探测脉冲的超宽带宽和超短脉宽,还观测到了p掺杂硅中的亚皮秒激发态声子波包振荡。

Abstract:

An improved scheme of optical pump terahertz probe (OPTP) technique was proposed. Using an ultrashort broadband terahertz (THz) pulse of air-induced plasma radiation ionized by a two-color femtosecond laser field as the probe pulse, the photo-excited dynamics in silicon was characterized with the improved OPTP, and the capability of the OPTP system based on the improved scheme of this paper was verified through a characterization process. The pump depth of silicon increase with higher pump power, so that the pump depth of 400nm pump pulse is greater than that of 800nm pump pulse. The pump depth of p-doped silicon is the largest, followed by intrinsic silicon, and the smallest for n-doped silicon while using 400nm pump pulse. However, the pump depth of p-doped silicon is the largest, followed by n-doped silicon, and the smallest for intrinsic silicon while using 800nm pump pulse. Furthermore, based on the ultrawide bandwidth and ultrashort pulse width of the probe pulse, the sub-picosecond phonon wavepacket oscillation in excited state is observed.