Dependence of Electron Temperature on the Incident Microwave Power in the Photo-Excited GaAs/AlGaAs 2D Electron System*

We examined the influence of microwave radiation on both amplitude of Shubnikov-de Haas (SdH) oscillations and null magnetic field longitudinal magnetoresistance at low temperatures, T<4.2 K, in GaAs/AlGaAs Hall bar devices. SdH oscillations have been analyzed over the parameter space given by 2.3<ω_c/ω<5.2, where ω_c=eB/m*, ω=2πf, B is the magnetic field, m* is the effective mass and f is the microwave frequency. Microwave radiation over the frequency range 30≤f≤100 GHz with peak source power 1≤P≤10 mW served to photo-excite a high mobility (10⁷cm²/Vs). 2D electron system (2DES) as magnetoresistance traces were obtained as a function of the microwave power P and T. Then, fits of the SdH oscillations line shape served to extract the electron temperature (T_e) as a function of P and T over the above-mentioned parameter window. Theory has proposed that, in the ω_c/ω≥1 regime, both the electron temperature and radiation energy absorption rate (S_p) exhibit relatively constant response, while in ω_c/ω≤1 regime, both T_e and S_p exhibit oscillatory behavior. We compare the results of this experimental study with the theoretical predictions and correlate the T_e and P.