Acoustic-phonon emission angle in selectively doped AlGaAs-GaAs-AlGaAs single quantum wells

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Abstract
A detailed theoretical study of the emission rate of the acoustic (AC) phonons is presented for AlGaAs-GaAs-AlGaAs single quantum wells (SQWs). The electron interacting with AC phonons via the deformation potential and piezoelectric coupling is taken into account, We consider the situations where one and two electronic subbands are occupied by electrons, using the results obtained from our self-consistent calculations on the electronic structure. The angle and energy dependences of the AC phonons generated in a GaAs-based two-dimensional electron gas (2DEG) are determined entirely by momentum and energy conservation during the electron-phonon scattering event, in contrast with the process of phonon generation in Si-based structures. Our results show that, in the phonon frequency range omega Q approximately 1012 Hz, the phonons with higher frequency can be detected at smaller emission angles. The phonons generated through the intersubband scattering processes have a more marked angle dependence and larger emission rate than those generated by intrasubband scattering processes.