IMAGING THE ELECTRON-PHONON INTERACTION IN THE 2D ELECTRON-GAS

Ballistic phonon imaging techniques have been used to study the electron-phonon interaction in the 2D electron gas (2DEG). Anisotropies in the phonon wavevector distribution arise out of the requirements for energy and momentum conservation when a phonon is emitted or absorbed and from the angular dependence of the electron-phonon coupling. Images of the phonon absorption by the 2DEG in Si MOSFET devices are presented and compared with theoretical (Monte-Carlo) simulations. In the quantum Hall regime it is shown that phonons are not emitted or absorbed in the bulk of the 2DEG and that dissipation and phonon scattering processes are confined to two opposite corners of the device.