Picosecond time-resolved Raman studies of the expansion of the electron-hole plasma in Si

The lateral expansion of photoexcited electron-hole plasma in Si is examined by picosecond time-resolved Raman scattering. The experimental results are consistent with the conclusion reached on a longer (nanosecond) time scale by Steranka et al., and show that at T=35 K, electron-hole plasma with n3×1018 cm-3 expands laterally at below sonic velocities on the 100-ps to 10-ns time scale.