Electrical Field Analysis of Nanoscale Field Effect Transistors

Abstract

Numerical simulations have been performed to analyze the electric field inside nanoscale field effect transistors with channel lengths Lch of 2 and 4 nm. Our electrostatic analyses characterize the electric field distribution inside the device structure when the ratio of dielectric thickness Tox to Lch (Tox/Lch) ranges from 0.2 to 50. At constant drain voltage, the relationship between the gate voltage Vg and Tox/Lch in the field distribution was investigated. Near the interface, the field intensity changes significantly and depends on Vg, Tox/Lch and on the distance from the interface. Vg has a strong effect on channel field for a small Tox/Lch (0.2–0.66). This effect decreases but remains significant when Tox/Lch increases in the range of 0.66–5. On the other hand, for Tox/Lch on the order of 5, Vg has a limited impact on the channel field and becomes negligible as Tox/Lch increases up to 50. We confirmed Kagen et al.'s suggestion that the values of Tox and Lch need to be properly selected to obtain functional nanoscale field effect transistors. However, we found that the gating effect should be included in device models for much higher of Tox/Lch values. Moreover, our results approximately corresponded to related work published by Damle et al.