Shot noise in negative-differential-conductance devices

Abstract

We have compared the shot-noise properties at T = 4.2 K of a double-barrier resonant-tunneling diode and a superlattice tunnel diode, both of which exhibit negative differential-conductance (NDC) in their current-voltage characteristics. While the noise spectral density of the former device was greatly enhanced over the Poissonian value of 2eI in the NDC region, that of the latter device remained 2eI. This result implies that charge accumulation, not system instability, is responsible for shot-noise enhancement in NDC devices.

Self-consistent simulation of quantum shot noise in nanoscale electron devices

“…2 are in good agreement with the experimental results obtained by several different groups, with different resonant heterostructures. [12][13][14] Let us mention that scattering (apart from the electron-electron interaction) is not considered here and it can modify present results. In principle, our approach can accurately deal with additional scattering mechanisms by introducing their interaction/potential directly into the Hamiltonian [Eq.…”

“…As a test, we have applied our approach to study current fluctuations on standard RTD and our numerical results are in good agreement with previous predictions 8,12,13 and experimental results. [12][13][14] We believe that the present approach opens a new path for the simulation of electron devices of nanometric dimensions. At such dimensions, pure QM effects (like tunneling or quantization) coexist 19,20 with classical electrostatic phenomena (such as Coulomb blockade), and the ancient Poisson equation becomes as meaningful as the prevalent Schrödinger equation for the correct understanding of actual mesoscopic devices.…”

Noise-Induced Oscillations and Their Control in Semiconductor Superlattices

“…It is well known that microscopic random fluctuations essentially affect the transport mechanisms in semiconductor nanostructures [Blanter & Büttiker, 2000;Kießlich et al, 2003;Song et al, 2003;Zhao & Hone, 2000]. They usually smear out and deteriorate the regularity in charge transport.…”

Shot-noise characteristics of triple-barrier resonant-tunneling diodes

“…This behavior is qualitatively similar to that found in sample C and in previous reports about noise in DBRTDs. 2,3,4,8 The deviation of the shot noise from the Poissonian value is best illustrated by plotting the Fano factor F , shown in Fig 3 along with the conductance. For the w 1 − n 1 peak, it is F = 0.55 ± 0.06 at 0.17V (the lowest voltage at which the current is sufficiently high to make a meaningful determination of noise in our set-up) and then F increases gradually, passing the value of 1 and reaching a local maximum of 1.4 when the differential conductance is negative and has a minimum value (at V = 0.23V).…”

“…7 Experimentally, it has been shown that the larger the absolute value of the negative differential conductance, the larger the noise enhancement, 4 and it has been unequivocally established that charge accumulation is essential to the enhancement of shot noise in a DBRTD. 8 Shot-noise measurements in DBRTDs have been limited to devices with relatively thick barriers, in which tunneling is sequential. Although several calculations have shown that in multiple-barrier structures the shotnoise reduction should be independent of whether the electronic transport is sequential or coherent, 9 other calculations have predicted a smaller shot noise when the process is coherent.…”