Study of drain induced barrier lowering (DIBL) effect and subthreshold characteristics of fully-depleted Ge NMOS with P-substrate

摘要

In this paper, the structure of fully-depleted Ge NMOS with P-substrate (FDP-NMOS) is proposed. The DIBL effect of fully depleted GeOI NMOS (FD-NMOS) and FDP-NMOS has been studied based on the simulation results. It is demonstrated that DIBL of FD-NMOS occurs at the deep bulk of channel before the surface. From the current-voltage (I_D-V_G) characteristics, the DIBL effect, the leakage current and the on-state current are determined. The results indicate that with the doping concentration of P-substrate (N_B) increasing, the DIBL effect is lower and the leakage current decreases significantly. Therefore, the FDP-NMOS has excellent subthreshold characteristics. When N_B is 10 × 10~(17)/ cm3, the subthreshold swing is 76.8 mV/dec and the on/off ratio is 1.65 × 10~8, respectively. The on/off ratio of FDP-NMOS increases more than 4 orders compared with the FD-NMOS and the experimental results.