The acoustoelectric effect resulting from the interaction between a longitudinal acoustic wave at 13 MHz and the two‐dimensional electron gas (2‐DEG) in a GaAs/AlGaAs heterostructure is described. Quantum oscillations in the acoustoelectric response as a function of applied magnetic field at a temperature of 4.2 K are observed. A simple model explaining how the acoustoelectric signal is produced, is discussed. In addition, the acoustoelectric signal obtained at temperatures of 4.2, 77, and 300 K for a wide range of gate voltages is described.

Phonon scattering by a 2-DEG has been studied using ballistic heat pulses. Heat pulses generated by a gold thin-film resistance heater have been detected by a CdS bolometer after passing through a 2-DEG in the inversion layer of a Si-MOSFET held at 4.2K. The detected ballistic phonon pulses have been examined as a function of gate voltage and applied magnetic field. At a magnetic field of 5T the pulse height oscillates with an amplitude of about 0.5% of the initial pulse height and with a period which is identical to the period of Shubnikov-de Haas oscillations in electrical conductivity.

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