Real-Time Observation of Ultrafast Carrier and Phonon Dynamics in p-Type Silicon

Abstract

In time-resolved refl ectivity measurements with 10-fs laser pulses at 780 nm, ultrafast carrier and phonon dynamics in p-type Si are observed. An enhancement in anisotropic state-fi lling occurs, indicating that the lowered Fermi level due to the p-type doping produces the anisotropic hole distribution. The larger frequency shift and the shorter lifetime observed in coherent phonons than those observed in Raman measurements indicate both excited carriers and doped carriers renormalize coherent phonons. The initial phase shift of coherent phonons induced by p-type doping is attributed to the anisotropic hole distribution.