The effect of an intense terahertz irradiation on electron transport in two-dimensional semiconductors

We study theoretically the electron transport in GaAs-based quasi-two-dimensional systems under the influence,of an intense terahertz electromagnetic irradiation, using a balance equation approach in which the slowly varying part of the centre-of-mass velocity is distinguished from the rapidly oscillating part of it. Electron scatterings by charged impurities, and acoustic and polar optical phonons are considered and up to as many as [n] = 60 multiphoton channels are taken into account. The carrier mobility and the electron temperature of a typical GaAs quantum well system are calculated in the limit of small de drift velocity (small de field) as functions of the radiation-field strength for various frequencies in the range from 1 to 10 THz at lattice temperature T = 10, 77, 150 and 300 K. We find that at low lattice temperature (T = 10 K), de mobility decreases monotonically with increasing strength of the radiation field, and lower frequency generally has a stronger effect in suppressing the mobility, in agreement with the experimental observation. At room temperature, on the other hand, the present theory predicts an enhancement of the de mobility due to irradiation with a THz field.