Effect of Contacts on Quantum Transport in Nanostructures

In quasiballistic nanoscale devices, the process of relaxation towards a steady state cannot be attributed to carrier scattering. Rather, carrier exchange between the active region and the rapidly dephasing contacts is the mechanism governing relaxation. In this paper, we present a novel technique for the treatment of quantum transport in quasiballistic semiconductor nanostructures. The approach utilizes a first-principles model interaction between the current-limiting active region and the contacts. With the use of the model interaction and by accounting for the energy relaxation in the contacts due to the electron- electron interaction, irreversible evolution of the active region´s many body statistical operator is derived in the Markovian approximation. Specifically, analytical steady-state distribution functions are derived for a generic two-terminal nanostructure, and used to obtain the steady-state I-V curves for the cases of a resonant-tunneling diode and an nin diode.