Quantum-mechanical analysis of the electrostatics in silicon-nanowire and carbon-nanotube FETs
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- 作者：Elena Gnani ; Alex Marchi ; Susanna Reggiani ; Massimo Rudan and Giorgio Baccarani
- 关键词：Electrostatic analysis ; Quantum-mechanical simulation ; Top-gate carbon nanotube FET ; Π ; -gate FET ; High-κ ; dielectrics
- 刊名：Solid-State Electronics
- 出版年：2006
- 出版时间：April 2006
- 年：2006
- 卷：50
- 期：4
- 页码：709-715
- 全文大小：495 K
文摘
In this work we investigate the electrostatics of the top-gate carbon-nanotube FET (CNT-FET) and the silicon-based Π-gate FET at the ITRS 22 nm node. In order to do so, we solve the coupled Schrödinger and Poisson equations within the cross-section of each device, and compare the channel-charge and capacitance curves as functions of the gate voltage. This study shows that, for a fixed cross-sectional area, the quantitative differences between the two devices are small both in terms of charge and capacitance. The use of a classical model for the Π-gate FET shows instead that the resulting discrepancies with respect to the quantum-mechanical (QM) model are very relevant using both the Boltzmann and Fermi statistics. Thus, accounting for quantum-mechanical effects is essential for a realistic prediction of the device on-current and transconductance at the feature sizes considered here. The effect of high-κ dielectrics is also addressed. As opposed to planar-gate devices, the electrostatic performance of Si-based Π-gate FETs and CNT-FETs is not adversely affected by the use of different insulating materials with the same equivalent oxide thickness. As a consequence, not only do high-κ dielectrics relieve the gate-leakage problem; they also improve the device performance in terms of the gate-control effectiveness over the channel.