Shot noise of quantum ring excitons in a planar microcavity

Shot noise of quantum ring (QR) excitons in a p-i-n junction surrounded by a microcavity is investigated theoretically. Some radiative decay properties of a QR exciton in a microcavity can be obtained from the observation of the current noise, which also gives extra information about one of the tunnel barriers. A different noise feature between the quantum dot (QD) and QR is pointed out, and may be observed in a suitably designed experiment.

Figure 1

(Color online) (a) Schematic description of a QR inside a p-i-n junction surrounded by a planar microcavity with length $L$. (b) Energy-band diagram of a QR in the p-i-n junction.

Figure 2

Fano factor as a function of cavity length $L$. The vertical and horizontal units are $\left[S_{I_R}\left(0\right)\right]∕\left(2eI\right)$ and ${\lambda }_0∕2$, respectively. The inset shows the radiative decay rate of a QR exciton in a planar microcavity.

Figure 3

Fano factor as a function of the decay rate for different electron-side tunneling rate ${\Gamma }_L=0.01{\gamma }_0$ (solid line), $0.05{\gamma }_0$ (dashed line), and $0.1{\gamma }_0$ (dashed-dotted line). The hole-side tunneling rate is fixed $({\Gamma }_R={\gamma }_0)$.

Figure 4

Fano factor of QD (solid line) and QR (gray dashed line) excitons as a function of energy gap $\epsilon$. The vertical and horizontal units are $\left[S_{I_R}\left(0\right)\right]∕\left(2eI\right)$ and $2hc∕{\lambda }_0$, respectively. The dashed-dotted line represents that if the free-space decay rate of the QR exciton is enhaced by a factor of $2({\gamma }_0\to 2{\gamma }_0)$, the shot noise is also enhanced.