Shot-noise anomalies in nondegenerate elastic diffusive conductors

Abstract

We present a theoretical investigation of shot-noise properties in nondegenerate elastic diffusive conductors. Both Monte Carlo simulations and analytical approaches are used. Two interesting phenomena are found: ͑i͒ the display of enhanced shot noise for given energy dependences of the scattering time, and ͑ii͒ the recovery of full shot noise for asymptotic high applied bias. The first phenomenon is associated with the onset of negative differential conductivity in energy space that drives the system towards a dynamical electrical instability in excellent agreement with analytical predictions. The enhancement is found to be strongly amplified when the dimensionality in momentum space is lowered from three to two dimensions. The second phenomenon is due to the suppression of the effects of long-range Coulomb correlations that takes place when the transit time becomes the shortest time scale in the system, and is common to both elastic and inelastic nondegenerate diffusive conductors. These phenomena shed different light in the understanding of the anomalous behavior of shot noise in mesoscopic conductors, which is a signature of correlations among different current pulses.

Noise temperature reduction by doping in ballistic n+–n–n+nanodiodes

“…Within a semiclassical approach, the description of the transport and noise properties is given by means of the Vlasov equation self-consistently coupled to the Poisson equation and supplemented by appropriate boundary conditions, as detailed in [11,12]. The boundary conditions fix the mean velocity distribution function and the statistics of injected carriers.…”

Electronic transport and noise in ballistic n n n semiconductor nanodiodes

“…The low frequency solution of the model presented in section 3 can be obtained in fully analytical form by following a similar procedure to the one presented in [16] for n + -i-n + ballistic diodes. Below we present the final results for the currentvoltage (I -V ) characteristics and the low frequency spectral density of the current fluctuations.…”

“…Below we present the final results for the currentvoltage (I -V ) characteristics and the low frequency spectral density of the current fluctuations. For any details concerning the calculations we refer to [16].…”

“…Following the procedure presented in [16], S I (0) can be calculated in closed analytical form for the model presented in section 3. The final result can be written in the following compact form:…”

“…This is not the case, however, on what concerns the noise properties. The existing experimental data [13,14] are scarce and the theoretical calculations provide only some estimates valid in the space charge limited transport regime based on the theory of vacuum tubes [15] and of n + -i-n + ballistic diodes [16].…”