Calculations of high-frequency response of two-dimensional hot electrons in GaAs quantum wells

Abstract

Small-signal ac mobility of two-dimensional (2D) degenerate hot electrons in a GaAs square quantum well is studied on a heated drifted Fermi–Dirac distribution function for the carriers. Carrier energy loss via longitudinal optic (LO) phonons, and the momenta losses via LO, acoustic and ionized impurity scatterings are considered. The ac mobility is found to drop off with frequency beyond 100 GHz although the drift velocity starts to lag behind the applied field at a lower frequency. The ac mobility μac and the phase angle φ increase with the rise of the channel width and the 2D carrier concentration. However, the 3-dB cut-off frequency f3 dB is found to decrease with increasing channel width. The values of μac and f3dB are higher but those of φ are lower at 300 K than that at 77 K.