In a series of systematic optical pump–terahertz probe experiments, we study the density-dependent electron scattering rate in photoexcited GaAs in the regime of strong carrier diffusion. The terahertz frequency-resolved transient sheet conductivity spectra are perfectly described by the Drude model, directly yielding the electron scattering rates. A diffusion model is applied to determine the spatial extent of the photoexcited electron-hole gas at each moment after photoexcitation, yielding the time-dependent electron density, and hence the density-dependent electron scattering time. We find that the electron scattering time decreases from 320 to 60 fs, as the electron density changes from 1015 to 1019 cm−3.

Appl. Phys. Lett.

Mics, Z, D'Angino, A, Jensen, S.A, Bonn, M, & Turchinovich, D. (2013). Density-dependent electron scattering in photoexcited GaAs in strongly diffusive regime. Appl. Phys. Lett., 102(23, Article number: 231120), 1–3. doi:10.1063/1.4810756