An Analytic Solution of Channel Potential and Drain Current for an Undoped Symmetric DG MOSFET Using SiO2 and High K Gate Dielectrics

In this work, we have presented a new analytical potential and current model for an undoped symmetric double- gate (DG) MOSFET which is valid from low to high drain-source voltages. The models are derived from an analytical solution of 2-D Poisson's equation. From the analytic solutions, explicit expressions for potential, electric field, mobile charge density and current have been derived. Simulations are done with the gate material SiO₂ (k = 3.9) and high k dielectric material HfO₂ (k = 22). Our results are in close agreement to the numeric device simulator ATLAS as well as other published and experimental results.

I. INTRODUCTION

THE DOUBLE-GATE (DG) MOSFET is one of the most promising architectures for scaling CMOS devices down to nanometre size, since they allow a considerable reduction of the short-channel effects (SCEs), such as threshold voltage roll-off, drain-induced barrier lowering (DIBL), and subthreshold slope degradation, compared to planar single-gate MOSFETs. DG MOSFET exhibits almost ideal sub-threshold swing (60mv/dec), lower output conductance and higher drive current. Moreover, in DG MOSFETs, the channel material is preferred to be undoped as absence of dopant atoms in the channel material eliminates adverse effects, such as mobility degradation and random microscopic fluctuations of dopant atoms, which can lead to unwanted dispersion in the device characteristics. The use of high dielectric become prominent in further scaling down the MOSFET as well as improving the performance.