Novel Analytical Model for Computing Subthreshold Current in Heterostructure p-MOSFET incorporating Band-To-Band Tunneling Effect

Abstract

Abstract Subthreshold current for heterostructure pMOSFET is analytically explored as a function of applied bias for Si-SixGe1-x material system in presence of band-to-band tunneling. Threshold voltage of the structure is calculated considering body effect for different structural parameters, and mole fraction of Ge is chosen as 0.28 for that operating point where 2DEG is yet to be formed, and thus suitable for estimating subthreshold conduction. Using this optimum structure, BTBT effect is incorporated to measure the drain current for a range of source-to-gate voltage (VSG), and results suits in excellent with available experimental data for very low and higher values of source-to-drain voltage (VSD). Result is also computed in absence of tunneling effect, and drastic variation is observed which speaks in favor of our proposed model of subthreshold conduction. A monotonic decrease of subthreshold slope is observed with increase of VSG, which speaks for the optimum biasing criteria for operation of the device in order to minimize the leakage current. Results are in favor of applying the model for sub-22 nm FinFET or even sub-10 nm TFET devices.