Ultrafast transient grating scattering studies of carrier dynamics at a silicon surface Original Research Article

Transient grating scattering, in the reflective configuration, is used to study the dynamics of photoexcited carriers in the near-surface region of silicon on femtosecond and picosecond time scales. A rich variety of carrier relaxation processes including carrier dephasing, energy relaxation, and ambipolar diffusion are manifested in the grating scattering signal. Strong dependence of relaxation and diffusion rates on carrier concentration, reflecting the effects of charge screening at higher carrier concentrations, has been observed.