Quantum transport of a nanowire field-effect transistor with complex phonon self–energy

Abstract

In this work, the impact of the real part of the phonon self-energy on the transfer characteristics of a silicon nanowire transistor is investigated. The physical effects of the real part of the self-energy are to create a broadening and a shift on the density of states. This increases the drain current in the sub–threshold region and decreases it in the above–the–threshold region. In the first region, the current is increased as a result of an increase of charge in the middle of the channel. In the second one, the electrostatic self–consistency or the enforcement of charge neutrality in the channel reduces the current because a substantial amount of electrons are under the first subband and have imaginary wave vectors. The change in the phonon–limited mobility due to the real part of self–energy is evaluated for a nanowire transistor and a nanowire in which there is not source to drain barrier. We also assess the validity of Mathiessen's rule using the self–consistent NEGF simulations and the Kubo–Greenwood formalism.