Photoassisted Tunneling Through Semiconductor Nanostructures

Abstract

We analyze theoretically the effect of a laser on the stationary tunneling current through a semiconductor double barrier, when a magnetic field is applied parallel to the current.

The coherent and sequential contributions to the magnetotunneling current are modified by the light due to the photon emission and absorption processes which assist the tunneling of electrons through the structure. Prom our calculations we conclude that the coherent contribution is more affected by the light than the sequential one. We observe that the effect of the light can be controlled by tuning the ratio between the cyclotron and the photon frequencies. When this ratio is one the effect of the light on both coherent and sequential magnetotunneling is drastically modified.

The light acts charging and discharging the well and therefore modifies the number of Landau levels contributing to the current.

We have evaluated this effect for sequential magnetotunneling, where the Landau levels occupation into the well determines the tunneling current. We have performed a selfconsistent calculation for the sequential tunneling current through a DB by solving simultaneously the Schrodinger and the Poisson equations. The light assists the tunneling modifying the charge density in the well and therefore the selfconsistent current through the structure, which presents new features in the presence of light. This effect has been analyzed for different samples, field frequencies and intensities.