Two-dimensional(2D) subthreshold current and subthreshold swing modeling of double-material-gate(DMG) strained-Si(s-Si) on silicon-germanium(SiGe) MOSFETs.

Abstract

In this dissertation analysis of double-material-gate (DMG) strained-Si (s-Si) channel on SiGe substrate MOSFET is done in the subthreshold region of operation and hence the behaviour of leakage current and subthreshold swing is studied. The advantages of dual material gate (DMG) structure to suppress various short channel effects are studied. Also the effect of introducing strain in the channel is incorporated as it is beneficial in terms of improving the mobility of carriers in the channel. A two dimensional (2D) analytical device model is derived by solving Poisson’s equation and by approximating the potential profile as a parabola in the channel. A detailed analysis of double-material-gate (DMG) strained-Si (s-Si) on SiGe MOSFET is done in the subthreshold region of operation in terms of subthreshold current and subthreshold swing while varying different device parameters such as gate length, amount of strain, control gate to screen gate length ratio, control gate to screen gate metal work function ratio to investigate the advantages of incorporating strain and double material gate metal in the proposed device. Thereafter two dimensional (2D) simulation of the device is carried out in the device simulator ATLASTM by Silvaco Inc. The data extracted from the simulator is used for verification of the predicted model.