Dissipative transport of thermalized electrons through a nanodevice

An equilibrium distribution function which corresponds to thermalization of electrons in contacts due to scattering processes is introduced for the purpose of reformulation of the inflow boundary conditions for the Wigner kinetic equation. The importance of the proposed concept for more realistic descriptions of transport phenomena in nanodevices is illustrated by determination of characteristics of the nanowire in cases of dissipative and dissipationless states of its active region. Quantitative results show how transport characteristics of the nanodevice are modified by the contacts.

Figure 1

(a) Schematic of the nanowire with active region containing embedded GaAs/${\mathrm{Al}}_{0.3}{\mathrm{Ga}}_{0.7}\mathrm{As}$ double-barrier structure. (b) Potential energy profile along the axis of the nanowire resulting from the conduction band discontinuity, and for the applied bias voltage $V=50$ mV.

Figure 2

The Wigner distribution function calculated for the bias voltage corresponding to the peak of the current, (a) without scattering and (b) for scattering times ${\tau }_{\mathrm{\Gamma }}=15$ fs and $\tau =50$ fs.

Figure 3

(a) Current-voltage characteristics of the nanowire obtained when no scattering processes of any kind are included, and illustrating the definitions of the peak (valley) voltages, $V_{p\left(v\right)}$, and currents, $I_{p\left(v\right)}$. The characteristics calculated for varying relaxation time, ${\tau }_{\mathrm{\Gamma }}$, corresponding to the scattering processes in the contacts, is presented in (b) for the case without scattering inside the nanodevice, (c) For $\tau =300$ fs, and (d) for $\tau =50$ fs. In (b), (c), and (d), the blue dashed line shows the current for $\mathrm{\Gamma }=0$, while the gray dotted line indicates, for comparison, the characteristics shown in (a).

Figure 4

Relative change of the peak current as a function of the parameter $\mathrm{\Gamma }$ for $\tau =50,100,300$ fs. The dashed gray line corresponds to the case without scattering inside the nanowire.

Figure 5

The absolute value of the negative resistance $R_n$ for $\tau =50,100,300$ fs, and for the case when no scattering inside the nanowire is assumed (dashed gray line). The inset shows the peak-to-valley ratio (PVR) as a function of the parameter $\mathrm{\Gamma }$.