## Results and Discussion
### GIDL and I\({}_{\text{ON}}\)/I\({}_{\text{OFF}}\) Ratio  
Figure 4a presents the typical subthreshold characteristics of FinTFTs with a narrow \(W_{0}\) (W40). The leakage current increased with a larger negative gate bias, which was due to GIDL. Increasing \(L_{EX}\) can not only improve the breakdown voltage but also suppress GIDL. For multi-gate devices such as a FinFET with a narrow channel width, L-BTBT instead of conventional T-BTBT is dominant [31]. L-BTBT occurs when a high drain bias (\(V_{\text{DS}}\)) and low gate bias (\(V_{\text{GS}}\)) are applied and the valence band in the body becomes higher than the conduction band in the drain region; these factors increase the GIDL current. The typical subthreshold characteristics of a device with a wide \(W_{0}\) (W200) are shown in Figure 4b for comparison. The leakage current is almost constant below \(V_{\text{GS}}=-1\) V because of the slight change in the longitudinal energy band, which bends when \(V_{\text{GS}}\) is varied. The longitudinal energy band diagrams of W40 and W200 with \(V_{\text{GS}}\) = 0 and \(-3\) V are presented in Figure 5. Weak gate controllability in W200, which is similar to that in the conventional planar structure, results in a minor influence of gate bias on the longitudinal energy band (Figure 5b). However, the bending of the longitudinal energy band becomes evident for W40 and is caused by a large longitudinal electrical field at the intrinsic drift /\(N^{+}\) junction (Figure 5a). Figure 4: Subthreshold characteristics of (**a**) W40 and (**b**) W200 with various \(L_{EX}\) at \(V_{\text{DS}}\) = 18 V.  
Figure 3: Electric field distribution of (**a**) W40 and (**b**) W200 with \(L_{EX}\) = 0 and \(L_{EX}\) = 0.6 \(\upmu\)m at \(V_{\text{DS}}\) = 20 V (before breakdown). To understand the dependence of GIDL on \(L_{EX}\), the longitudinal energy band diagrams were analyzed. Figure 6 shows the longitudinal energy band diagrams of W40 with \(L_{EX}\) = 0 and 0.6 \(\upmu\)m at \(V_{GS}\) = \(-\)3 V and \(V_{DS}\) =18 V. For FinTFTs with \(L_{EX}\) = 0.6 \(\upmu\)m, an increase in the depletion width and a decrease in the electric field resulted in less pronounced band bending, and thus a wider tunneling width compared with FinTFTs with \(L_{EX}\) = 0 \(\upmu\)m.  
Figure 7a shows variation in the GIDL current with a wide drain length for W40 and W200 at \(V_{GS}\) = \(-\)3 V and \(V_{DS}\) = 18 V. The values in Figure 7a were obtained from the simulation results. The GIDL current of W40 and W200 without the BTBT model are also shown in Figure 7a. The GIDL current was almost constant when the BTBT model was not considered. The values for W40 and W200 are indicated by the black line with a hollow symbol and red line with a hollow symbol, respectively. W40 with \(L_{EX}\) = 0 \(\upmu\)m has a large GIDL current because of the enhanced L-BTBT. As a result, the GIDL current decreased as \(L_{EX}\) increased. The GIDL current of W40 with \(L_{EX}\) = 0.6 \(\upmu\)m had a value close to that observed at the black line with a hollow symbol. However, the device with a wide W\({}_{0}\) (W200) exhibited a small change in GIDL current with an increase in \(L_{EX}\), and all values of the GIDL current were close to the red line with a hollow symbol. Notably, the GIDL current of W40 with \(L_{EX}\) = 0.6 \(\upmu\)m was lower than that of W200; this indicates that a device with a wide drain can effectively reduce the GIDL current. Figure 7b shows the electric field distribution of W40 and W200 with \(L_{EX}\) = 0 and 0.6 \(\upmu\)  
Figure 5: Longitudinal energy band diagrams of (**a**) W40 and (**b**) W200 with \(V_{GS}\) = 0 and \(-\)3 V.  
Figure 6: Longitudinal energy band diagrams of W40 with \(L_{EX}\) = 0 and \(L_{EX}\) = 0.6 \(\upmu\)m at \(V_{GS}\) = \(-\)3 V and \(V_{DS}\) = 18 V.  
at \(V_{GS}=-3\) V and \(V_{DS}=18\) V. The electric field peaks of W40 and W200 are located at the intrinsic drift/\(N^{+}\) junction.