Microwave conductivity of a confined superlattice

Microwave small-signal mobility of vertical conduction in the presence of a dc bias is investigated for cylindrically confined superlattices having various transverse diameters. At finite dc bias the differential mobility exhibits peculiar frequency-dependence, which stems from a decrease of the average inverse effective mass of carriers in conjunction with an increase of their average longitudinal energy, and is characterized approximately by a momentum and an energy relaxation time. It is found that the effective energy-relaxation time increases significantly as the transverse dimensions of the superlattice increase. PACS: 72.30.+q; 73.50.Mx