Impact of phonon scattering in Si/GaAs/InGaAs nanowires and FinFets: a NEGF perspective

This paper reviews our previous theoretical studies and gives further insight into phonon scattering in 3D small nanotransistors using non-equilibrium Green function methodology. The focus is on very small gate-all-around nanowires with Si, GaAs or InGaAs cores. We have calculated phonon-limited mobility and transfer characteristics for a variety of cross-sections at low and high drain bias. The nanowire cross-sectional area is shown to have a significant impact on the phonon-limited mobility and on the current reduction. In a study of narrow Si nanowires we have examined the spatially resolved power dissipation and the validity of Joule’s law. Our results show that only a fraction of the power is dissipated inside the drain region even for a relatively large simulated length extension (approximately 30nm). When considering large source regions in the simulation domain, at low gate bias, a slight cooling of the source is observed. We have also studied the impact of B Antonio Martinez [email protected] Anna Price [email protected] Raul Valin [email protected] Manuel Aldegunde [email protected] John Barker [email protected] 1 College of Engineering, Swansea University, Engineering East, Fabian Way, Crymlyn Burroughs, Swansea SA1 8EN, UK 2 School of Engineering, University of Warwick, Coventry CV4 7AL, UK 3 College of Science and Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT, UK the real part of phonon scattering self-energy on a narrow nanowire transistor. This real part is usually neglected in nanotransistor simulation, whereas we compute its impact on current–voltage characteristic and mobility. At low gate bias, the imaginary part strongly underestimated the current and the mobility by 50%. At high gate bias, the two mobilities are similar and the effect on the current is negligible.