Novel nonlinear transport phenomena in a triangular quantum well

The authors have measured transport properties in an AlGaAs/Al_xGa_1-xAs triangular quantum well whose energy spectrum has been varied by means of a gate bias. They have observed several nonlinear effects in the lateral conductance arising at positive gate voltages as the increasing Fermi level is moved towards the lowering energy positions of the excited subbands in the quantum well. They interpret the results in terms of electron population of the excited subbands in which electrons possess low mobility. Finally, they find new features at high lateral voltages which are considered to be evidence of previously predicted electro-phonon resonance.