Theoretical Investigation of Self-Heating Effect on AC Quantum Transport in p-Type FinFET in THz Frequency by AC Non-Equilibrium Green’s Function Method With Phonon Scattering

Abstract

In this article, a multiphysics simulation is performed to investigate the self-heating effect (SHE) on p-type FinFET ac quantum transport by introducing the temperature distribution obtained from dc quantum transport and heat conduction simulation into the ac non-equilibrium Green’s function with consideration of phonon scattering. The complicated valence band and hole-phonon scattering are captured by employing three-band $\boldsymbol {k}\cdot \boldsymbol {p}$ Hamiltonian and self-consistent Born approximation approach, respectively. The displacement current is considered in ac current density in addition to the conduction current by solving the Poisson equation and the ac non-equilibrium Green’s function (NEGF) equations self-consistently. The impact of the SHE on Y parameters, small-signal current gains, and cutoff frequency is investigated, and the corresponding underlying physical mechanism is also investigated by analyzing the ac current density spectrum and hole-density spectrum. The simulation results show that the SHE can affect the small-signal current gain and cutoff frequency by affecting ${Y}_{\text {DG}}$ rather than ${Y}_{\text {GG}}$ . For the device operated with gate voltage magnitude less than 0.4 V, the cutoff frequency and small-signal current gain can be increased because the hole energy is enhanced by the SHE, which means they can more easily cross or tunnel through the barrier, thereby increasing the amplitude of ${Y}_{\text {DG}}$ . In contrast, for the device operated with gate voltage magnitude greater than 0.5 V, the small-signal current gain and the cutoff frequency are decreased because the amplitude of ${Y}_{\text {DG}}$ is decreased by the enhanced hole-phonon scattering.