Quantum Mechanical Treatment on Modeling of Drain Current, Capacitances and Transconductances for Thin Film Undoped Symmetric DG MOSFETs

In this work we present a semi-analytical model for the current voltage and Capacitance-Voltage characteristics of nano scaled undoped symmetric double gate (DG) MOSFETs. This model uses a parabolic potential approximation for the body potential whose coordinate is normal or perpendicular to the interfaces in all regions of device operation. The carrier confinement phenomenon is considered and we calculate the surface electric field which is used to determine the inversion charge sheet density. The density is used in a compact classical model of the symmetric DG MOSFET as a core model. Quantum effects like the threshold voltage shift and increase in the effective oxide thickness are applied through some modifications to the core model. The results are verified by ATLAS device software. The comparison shows the high accuracy of the proposed model.

I. INTRODUCTION

Due to the downscaling of the device geometry into the nano region, increases the influence of quantum mechanical effects on the device characteristics. Along with tunneling, the effect of quantum confinement highly affects the characteristics of bulk, double gate (DG) MOSFET devices. Classical device simulation without quantum correction is no longer sufficient to provide accurate results as it predicts an exponential increase of the carrier concentration towards the gate oxide interface. However, due to the effect of quantum confinement, which affects the local density of states, the carrier concentration near the gate oxide decreases [23].