Electron–hole scattering in a highly excited semiconductor quantum well amplifier with terahertz-field-drifted carrier distributions: applications to all-optical switching

Anisotropic carrier–carrier scattering is theoretically investigated for high-density field-drifted electron–hole plasma distributions in semiconductor quantum wells. The drifted distributions, driven for example by a free-electron laser, are found to march microscopically and rapidly back to an isotropic, non-drifted plasma at the center of the Brillouin zone. This is in contrast to the single-species plasma case (p- or n-doped). We demonstrate that the presence of holes provides an efficient transport channel for electron relaxation and vice versa. Applications to all-optical switching and terahertz-optical control of direct-gap semiconductors are discussed.