Double-barrier coherent sound generator: a new device

We investigate a new device, a SASER, consisting of a double-barrier heterostructure (DBH) designed to generate ultra-high-frequency coherent sound. The device is tailored such that under the influence of an external bias, some of the electrons injected into the first excited level decay to the ground state by emitting LO-phonons. Due to the low energy and short wavelength of the phonon beam, this device can be used for imaging, for non-destructive characterization of nanostructures and to construct phonoelectronic systems (analogous to optoelectronics). In this paper we use a simple model to calculate the electronic current which takes into account the electron-phonon and electron-electron interactions. The electronic part is described in terms of a tight-binding Hamiltonian. Lattice dynamics are presented by a single LO-phonon mode confined inside the well for the primary beam and another single TA-phonon mode for the secondary one (F. Vallée, Phys. Rev. B49, 2460 (1994)). The electron-phonon interaction is described by a single transition matrix element between the two lowest states localized at the well. The electron and phonon populations, the current and the potential profile are calculated self-consistently. The results confirm the viability of the device, predicted in previous simplified calculations (S. S. Makler et al., Surf. Sci. 361, 239 (1996)).