Electrical field analysis of nanoscale field effect transistors

Numerical simulations have been performed to analyze the electric field inside nanoscale field effect transistors with channel lengths L-ch of 2 and 4 nm. Our electrostatic analyses characterize the electric field distribution inside the device structure when the ratio of dielectric thickness T-ox to L-ch (T-ox/L-ch) ranges from 0.2 to 50. At constant drain voltage, the relationship between the gate voltage V-g and T-ox/L-ch in the field distribution was investigated. Near the interface, the field intensity changes significantly and depends on V-g T-ox/L-ch and on the distance from the interface. V-g has a strong effect on channel field for a small T-ox/L-ch (0.2-0.66). This effect decreases but remains significant when T-ox/L-ch increases in the range of 0.66-5. On the other hand, for T-ox/L-ch on the order of 5, V-g has a limited impact on the channel field and becomes negligible as T-ox/L-ch increases up to 50. We confirmed Kagen et al.'s suggestion that the values of T-ox and L-ch 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 T-ox/L-ch values. Moreover, our results approximately corresponded to related work published by Damle et al.