Dynamics of Resonant Tunneling Domains in Superlattices: A Discrete Drift Model

Abstract

Transport in superlattices (SL) formed by weakly-coupled quantum wells under an applied electric field perpendicular to the layers is dominated by sequential resonant tunneling (Kazarinov and Suris, 1972; Esaki and Chang, 1974; Capasso et al., 1986). The current-voltage (I-V) response for photoexcited carriers in undoped SL is quite different for the low and high excitation powers. For the first case the I-V curve has maxima at the field corresponding to the alignment between the subbands of the neighboring wells. Under strong enough excitation the electric field throughout the SL becomes nonuniform by breaking up into domains with different field strength. The I-V curve for this case exhibits one or several plateau-like regions with regularly spaced oscillations (Grahn et al., 1990; Kwok et al., 1994). The number of oscillations is comparable to the number of periods in the SL. Domain formation results also in the time-periodic damped oscillations of the photocurrent and the photoluminescence spectrum experimentally observed by (1994).