Time-resolved carrier and phonon dynamics in the near surface depletion region of GaAs (100)
Journal
Proceedings of SPIE - The International Society for Optical Engineering
Journal Volume
4643
Pages
69-76
Date Issued
2002
Author(s)
Abstract
The coupling between photoexcited plasma and coherent LO phonons in n-type GaAs (100) was investigated via time-resolved second harmonic generation. In addition to standard pump-probe setup, a time-delayed second pump was applied to inject excess plasma in the sample. The initial pump impulsively launched coherent LO phonons and the following second pump photoexcited excess plasma in the near surface depletion region, where the excess plasma could interact with the coherent LO phonons. It was found that the coherent LO phonon mode dephased rapidly as excess plasma was injected. Meanwhile, the coherent LO-electron and LO-hole coupling modes could be clearly observed in the Fourier spectra. These coupling modes showed plasma density dependent frequencies. Their coupling frequencies and dephasing process were studied in detail. The experimental results agree with the simulation of carrier and phonon dynamics in the near surface depletion region of GaAs on sub-picosecond time scale.
Type
conference paper