Electronic transport and noise in ballistic n  n n semiconductor nanodiodes

Abstract

We present a semiclassical kinetic theory for the electronic transport and noise properties of ballistic n+ – n– n+ semiconductor nanodiodes. The theory is based on an exact solution of the Vlasov–Langevin kinetic equation self-consistently coupled to the Poisson equation, and takes into account the Pauli exclusion principle. The current–voltage characteristics calculated from the present theory perfectly agree with existing theoretical predictions. Concerning the noise properties, the theory offers the possibility of computing the current noise under all current regimes, thus overcoming the inherent limitations of existing theories.

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

“…In this case, the I-V characteristic is linear for 0 < V 3V T , with a resistance depending on the doping density; and then it displays a V 1/2 dependence for 3V T V V D . At the highest voltages, injected carriers dominate the characteristic, which becomes again doping independent and similar to the undoped case [11]. Concerning the noise temperature-voltage characteristics, the calculated curves for the above doping densities are displayed in figure 2.…”

“…where S I (0) is the spectral density of the current fluctuations in this frequency range, G = dI /dV is the differential conductance and k B is the Boltzmann constant. Since both S I (0) and G can be computed analytically [11], the noise temperature is obtained according to equation (1). The calculations have been performed for a 0.2 µm long GaAs n + -n-n + ballistic diode with five different channel doping densities: N D = 0 (undoped), 2 × 10 15 , 10 16 , 2 × 10 16 and 3 × 10 16 cm −3 .…”

“…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.…”

“…The transport properties of n + -n-n + ballistic diodes have been well understood since the mid 1980s [10]. Concerning the noise properties, only very recently a complete theoretical description of these structures applicable to all current transport regimes has been developed [11]. In the present paper we report on the dependence of the noise temperature, T n , of n + -n-n + ballistic diodes on the doping density of the ballistic channel.…”