Heating of a two-dimensional electron gas by the electric field of a surface acoustic wave
The heating of a two-dimensional electron gas by an rf electric field generated by a surface acoustic wave, which can be described by an electron temperature $T_e$, has been investigated. It is shown that the energy balance of the electron gas is determined by electron scattering by the piezoelectric potential of the acoustic phonons with $T_e$ determined from measurements at frequencies $f$= 30 and 150 MHz. The experimental curves of the energy loss $Q$ versus $T_e$ at different SAW frequencies depend on the value of $ω\barτ_ε$, compared to 1, where $ \bar τ_ε$ is the relaxation time of the average electron energy. Theoretical calculations of the heating of a two-dimensional electron gas by the electric field of the surface acoustic wave are presented for the case of thermal electrons ($ΔT \ll T$). The calculations show that for the same energy losses $Q$ the degree of heating of the two-dimensional electrons (i.e., the ratio $T_e/T$) for $ω\barτ_ε>1$ ($f$= 150 MHz) is less than for $ω\barτ_ε<1$ ($f$=30 MHz). Experimental results confirming this calculation are presented.