Influence of excitonic linewidth on resonant tunneling time of electrons in double quantum wells under electric fields

A modified coherent model, which includes the inhomogeneous broadening effect of the excitonic linewidth, of the resonant tunneling (RT) of electrons in double quantum wells is presented. The validity of the model is confirmed with the experiments and shows that the resonant tunneling process of electrons can be mostly explained by the simple coherent theory. We discuss the influence of linewidth on resonant tunneling time, which is strongly dependent on the barrier thickness LB, by introducing the contrast-ratio (Lambda) and the full width at half depth (FWHD) of the RT valley, and we found that (Lambda) first increases with increasing barrier thickness, reaches a maximum, and then decreases with a further increase of LB, in striking contrast to the Fabry-Perot (FP) analogy where a monotonous increase of the current peak-to-valley ratio is predicted. A decrease of the FWHD monotonously with increase of LB is also found. We discuss the potential application of our results in the design of tunneling devices.