Resonant enhancement of quantum well linewidths by pseudo-barrier energy levels

The density of states and linewidths are calculated for an Al_xGa_1-xAs/GaAs quantum well with a well width of 76 Å, a barrier width of 130 Å, and a barrier height of 268 meV under an applied electric field. We show that the linewidths become resonantly broadened by the interaction with the pseudo-barrier states in the infinite triangular well formed from potential discontinuities. This broadening corresponds to a linewidth increase of 2.5 times and to a reduction in the tunneling time by a factor of 0.4 over that with no resonant enhancement. These results have direct implications for designing infrared detectors, Stark effect modulators, and quantum well tunneling transistors.