Direct observation of effective mass filtering in InGaAs/InP superlattices.

By making transport measurements on InGaAs/InP superlattices we have been able to demonstrate a regime of rapid electron tunneling perpendicular to the layers in the presence of quantum hole localization, i.e. effective mass filtering. The experiments were conducted on multi quantum well and single quantum well samples in the form of p(+)n junctions and involved low temperature photo-induced capacitance and ac conductivity measurements, which easily resolved the 250Angstrom superlattice period, and deep-level transient spectroscopy (DLTS) observations of hole trapping in 60-80 Angstrom quantum wells.