Electron intersubband relaxation in doped quantum wells

The intersubband relaxation time of an electron is calculated by considering electron-electron and electron-phonon (bulk LO phonon) scattering in a GaAs quantum well. The relaxation time is derived and numerically evaluated within the random-phase approximation with full multiple subband and frequency-dependent screening. The electron scattering due to the coupled system of electrons and phonons is compared with the decoupled scattering where both electron-electron and unscreened electron-phonon scattering are considered separately. It is shown that the intersubband relaxation time is heavily influenced by the electron density in the well. It is also shown that at room temperature it is necessary to use the finite-temperature dielectric function to accurately determine the intersubband relaxation time.