The Effect of A Magnetic-Field on the Phonon Emission from A Hot 2-Deg in the Inversion Layer of A Silicon Mosfet

Phonon emission by a heated two dimensional electron gas in a magnetic field has been studied using heat pulse techniques. The 2-DEG was heated by applying electrical pulses to the MOSFET source-drain electrodes at constant gate voltage and the heat pulses detected by cadmium sulphide bolometers. Using constant power input to the 2-DEG the detected signal was found to decrease by up to 20% in a field of 7T. In a magnetic field phonons are emitted at the cyclotron frequency. At high fields the cyclotron phonons are severely attenuated by isotope scattering in the Si substrate. </jats:p

Quantum Oscillations in the Phonon-Scattering by A 2-Deg of A Si-Mosfet

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. </jats:p