Heating of a two-dimensional electron gas by the electric field of a surface acoustic wave

TL;DR

This study investigates how a surface acoustic wave heats a two-dimensional electron gas, combining experimental measurements at different frequencies with theoretical calculations to understand energy loss and electron temperature behavior.

Contribution

It provides a combined experimental and theoretical analysis of electron heating by surface acoustic waves, highlighting the frequency-dependent energy loss mechanisms and electron temperature rise.

Findings

Energy loss curves depend on the ratio of frequency to electron energy relaxation time.

Higher frequency (150 MHz) results in less electron heating for the same energy loss.

Experimental results agree with theoretical predictions.

Abstract

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 $\omega \bar{\tau}_{\epsilon}$, compared to 1, where $ \bar {\tau}_{\epsilon}$ 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 ($\Delta T \ll T$). 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 $\omega \bar{\tau}_{\epsilon}>1$ ($f$= 150 MHz) is less than for $\omega \bar{\tau}_{\epsilon}<1$ ($f$=30 MHz). Experimental results confirming this calculation are presented.