Terahertz photo-generated current in a two-dimensional quantum dot system

Abstract

The photo-generated current due to electronic transitions in a semiconductor planar quantum dot attached to outgoing leads is theoretically investigated. An electron is confined in the dot by a pure quantum mechanical effect, which is due to the higher ground state energy of the quantum wells forming the leads, as compared to the one in the dot. The dynamics of such a confined electron interacting with a light pulse is investigated by numerically solving a time-dependent Schrödinger equation within the effective mass approximation and goes beyond the lowest order perturbative approach. Our results show the coexistence of both linear and non-linear contributions to the photo-generated current in this system, sharply peaked at frequencies in the terahertz range, which are further tunable by the quantum dot radius. The peaks can be made even sharper as one adds a narrow constriction in the dot–leads connection. The details of the dependence of the peaks’ frequency, intensity, and sharpness on system parameters are discussed.