Enhanced Shot Noise in Resonant Tunneling via Interacting Localized States

Abstract

In a variety of mesoscopic systems shot noise is seen to be suppressed in comparison with its Poisson value. In this work we observe a considerable enhancement of shot noise in the case of resonant tunneling via localized states. We present a model of correlated transport through two localized states which provides both a qualitative and a quantitative description of this effect.

Full shot noise in mesoscopic tunnel barriers

“…All theoretical work [13][14][15][16] predicted shot noise suppression in the presence of localized states. However, a recent study by Safonov et al 17 also found enhancement of shot noise due to interacting localized states. They investigated the shot noise of a tunnel barrier in an n-GaAs metal-semiconductor fieldeffect transistor ͑MESFET͒.…”

“…A wide variety of noise behaviors due to localized states in mesoscopic systems have been studied both theoretically [13][14][15][16] and experimentally. [17][18][19][20][21] On the other hand, a clear demonstration of the shot noise behavior of an ideal tunnel barrier is still missing for semiconductor systems. In this paper, we report our observation of such a behavior in semiconductor tunnel barriers under various measurement configurations.…”

“…These results are similar to those from other groups. 17,19,20 the data requires information of the microscopic details ͑e.g., coupling between localized states and contacts͒ of the barrier. Figure 3 shows the results of similar measurements on four different barriers of the smaller size.…”

“…Both sets are substantially smaller than those studied by other groups. 12,17,18,21 These small samples, when pinched off to form tunnel barriers, should contain less localized states.…”

“…Such a point contact structure is different from the samples used in some of the previous studies of shot noise in tunnel barriers. 17 Two sets of barriers with different gate size were used in our measurements. The larger set has a size of W = 350 nm and L = 200 nm, the smaller set has W = 200 nm and L = 50 nm.…”