A center-potential-based threshold voltage model for a graded-channel dual-material double-gate strained-Si MOSFET with interface charges

An analytical center-potential-based threshold voltage model is developed for a symmetrical graded-channel dual-material double-gate strained-Si metal-oxide-semiconductor field-effect transistor (MOSFET) with interface charges by solving the two-dimensional (2-D) Poisson equation with suitable boundary conditions. The potential distribution of the device is determined by using the parabolic approximation method along the y-axis. This paper focuses mainly on the center-potential-based natural length to estimate the exact short-channel behavior of the device. Here, the leakage path is formed at the center rather than the surface of the channel. The proposed model is used to investigate the effects of different device parameters such as the strain in the Si channel, the channel length, and the thicknesses of the gate oxide and strained Si by performing extensive analysis on the center potential, threshold voltage, subthreshold swing, and short-channel effects. Considering its significance in the nanoscale regime, the hot-carrier-induced device degradation is also investigated. The proposed model is validated against numerical results obtained from technology computer-aided design (TCAD) simulations.