Coherent LO phonons generated by high-velocity electrons in two-dimensional channels and their impact on carrier transport

We show that Cerenkov generation of confined LO phonons by drifting electrons can be achieved in biased quantum wells (QWs). Both linear and nonlinear regimes of phonon generation are analyzed. The kinetic parameters of the drifting electrons are estimated by using momentum and energy balance equations for electron scattering by the confined optical phonons. Our findings suggest that high efficiency electrical generation of coherent optical phonons can be realized in two-dimensional structures with high drift velocities, such as AlAs/GaAs/AlAs and GaSb/InSb/GaSb QWs. Due to high conversion efficiency, the effect of current driven phonon generation can be an important mechanism of current suppression in two-dimensional channels where its contribution to saturation of current-voltage characteristics can compete with the contribution of intervalley transitions.