Comparison of Temperature Dependent Carrier Transport in FinFET and Gate-All-Around Nanowire FET

The temperature dependent carrier transport characteristics of n-type gate-all-around nanowire field effect transistors (GAA NW-FET) on bulk silicon are experimentally compared to bulk fin field effect transistors (FinFET) over a wide range of temperatures (25–125 °C). A similar temperature dependence of threshold voltage (VTH) and subthreshold swing (SS) is observed for both devices. However, effective mobility (μeff) shows significant differences of temperature dependence between GAA NW-FET and FinFET at a high gate effective field. At weak Ninv (= 5 × 1012 cm2/V∙s), both GAA NW-FET and FinFET are mainly limited by phonon scattering in μeff. On the other hand, at strong Ninv (= 1.5 × 1013 cm2/V∙s), GAA NW-FET shows 10 times higher dμeff/dT and 1.6 times smaller mobility degradation coefficient (α) than FinFET. GAA NW-FET is less limited by surface roughness scattering, but FinFET is relatively more limited by surface roughness scattering in carrier transport.

Electron Mobility due to Surface Roughness Scattering in Depleted GaAs Free-Standing Thin Ribbon

Electron mobility limited by surface roughness scattering in free-standing GaAs thin ribbon with an internal parabolic quantum well caused by surface state is investigated in detail. Based on analyzing the parabolic quantum well including the energy subband level, wave function and the confined potential profile in the thin ribbon by solving Schrödinger and Poisson equations self-consistently, the electron mobility could be investigated. Conclusion indicates that remote surface roughness (RSR) of the thin ribbon will change the two dimensional electron gas (2DEG) mobility through the medium of barrier height fluctuation of the parabolic well in atomic scale. Calculation results reveal that the 2DEG mobility decreases with increasing roughness amplitude, which is characterized in terms of the surface roughness height and the roughness lateral size.