Photovoltaic effect in bent quantum wires in the ballistic transport regime

A scheme for the generation of a photocurrent in bent quantum wires is proposed. We calculate the current using a generalized Landauer-Büttiker approach that takes into account the electromagnetic radiation. For circularly polarized light, it is demonstrated that the curvature in the bent wire induces an asymmetry in the scattering coefficients for left and right moving electrons. This asymmetry results in a current at zero bias voltage. The effect is due to the geometry of the wire which transforms the photon angular momentum into translational motion for the electrons. Possible experimental realizations of this scheme are discussed.

Figure 1

(Color online) Curved quantum wire irradiated by a circularly polarized electromagnetic wave (EMW) with the electric field component precessing in $x\text{−}y$ plane. It is assumed in our model that the curved quantum wire consists of two straight segments 1 and 3 connected by an arc 2.

Figure 2

(Color online) (a) A photocurrent as a function of the photon energy calculated for quantum wires having different arc lengths at fixed $R=25\mathrm{nm}$. (b) A photocurrent as a function of the arc length at $\hslash \omega =1\mathrm{meV}$. These plots have been obtained using $E_0=500\mathrm{V}∕\mathrm{m}$, $\mu =1\mathrm{meV}$, $T=10\mathrm{mK}$, and $m^{*}=0.067m_e$. The electric field amplitude $E_0=500\mathrm{V}∕\mathrm{m}$ corresponds to $33\mathrm{mW}∕{\mathrm{cm}}^2$ radiation power. All the curves other than $\phi =\pi ∕4$ in (a) have been vertically shifted by steps of $0.3\times {10}^{-11}\mathrm{A}$.

Figure 3

(Color online) A photocurrent as a function of the photon energy calculated (a) for different radiation intensities at $T=10\mathrm{mK}$ and (b) for different temperatures at $E_0=500\mathrm{V}∕\mathrm{m}$. The other parameters values are as in Fig. 2 with $\phi =\pi$ and $R=25\mathrm{nm}$.