ELECTRON DYNAMICS IN INTENTIONALLY DISORDERED SEMICONDUCTOR SUPERLATTICES

We study the dynamical behavior of disordered quantum well-based semic onductor superlattices where the disorder is intentional and short-ran ge correlated. We show that, whereas the transmission time of a partic le grows exponentially with the number of wells in an usual disordered superlattice for any value of the incident particle energy, for speci fic values of the incident energy this time increases linearly when co rrelated disorder is included. As expected, those values of the energy coincide with a narrow subband of extended states predicted by the st atic calculations of Dominguez-Adame et al. [Phys. Rev. B 51, 14 359 ( 1994)]; such states are seen in our dynamical results to exhibit a bal listic regime, very close to the WKB approximation of a perfect superl attice. Fourier transform of the output signal for an incident Gaussia n wave packet reveals a dramatic filtering of the original signal, whi ch makes us confident that devices based on this property may be desig ned and used for nanotechnological applications. This is more so in vi ew of the possibility of controlling the output band using a de-electr ic field, which we also discuss. In the conclusion we summarize our re sults and present an outlook for future developments arising from this work.