Potential Modeling of Oxide Engineered Doping-Less Dual-Material-Double-Gate Si–Ge MOSFET and Its Application

This paper discusses and analyzes, doping-less dual-material-double-gate (DL-DMDG) silicon-germanium (Si-Ge) MOSFET using oxide engineering technique. In oxide engineering technique, the dual material gate oxide is used in such a way that the permittivity of oxide under the control gate is less than that of screening gate (epsilon(1) < epsilon(2)). Such an arrangement enhances the electric field distribution in the channel region which increases the carrier velocity and hence, the trans-conductance. In this device charge plasma concept has been applied to an intrinsic Si-Ge substrate to induce n-type plasma. By using 2D-Poission equation analytical modeling of surface potential and electric field has been derived with respect to channel length and thickness. The analytical results have been validated with numerical device simulator. The result shows that the gate control over surface potential distribution increases by employing the oxide engineering techniques. Hence, SCEs are reduced. The electrostatic performance of proposed device has been compared with the double material gate oxide Si-Ge on insulator (DMGO-SGOI) MOSFET. Using device simulation, it has been obtained that the proposed device shows higher immunity to SCEs in comparison to DMGO-SGOI MOSFET. Further, source follower amplifier using NMOS transistor as current source has been designed using this device. Its drain current, trans-conductance, output voltage and gain have been investigated for different oxide materials. The DL-DMDG MOSFET incorporating oxide engineering technique offers higher amplification gain with the application of high permittivity oxide material at the screening gate.