Abstract
In this paper, we present full-band atomistic quantum transport simulations of single- and few-layer field-effect transistors (FETs) including electron-phonon scattering. The Hamiltonian and the electron-phonon coupling constants are determined from ab initio density-functional-theory calculations. It is observed that the phonon-limited electron mobility is enhanced with increasing layer thicknesses and decreases at high charge concentrations. The electrostatic control is found to be crucial even for a single-layer device. With a single-gate configuration, the double-layer FET shows the best intrinsic performance with an ON current, , but with a double-gate contact the transistor with a triple-layer channel delivers the highest current with . The charge in the channel is almost independent of the number of layers, but the injection velocity increases significantly with the channel thickness in the double-gate devices due to the reduced electron-phonon scattering rates in multilayer structures. We demonstrate further that the ballistic limit of transport is not suitable for the simulation of FETs because of the artificial negative differential resistance it predicts.
4 More- Received 11 May 2015
DOI:https://doi.org/10.1103/PhysRevB.92.035435
©2015 American Physical Society