IEEE Transactions on Nanotechnology

Archive for 2017

TNANO Article in focus: March-April 2017

Wednesday, April 12th, 2017

From the January 2017 issue of IEEE Transactions on Nanotechnology

Negative Capacitance for Boosting Tunnel FET performance

by Masaharu Kobayashi ; Kyungmin Jang ; Nozomu Ueyama ; Toshiro Hiramoto
T-NANO, Vol. 16, Issue 2, pp. 253 – 258, January 2017.


Abstract: We have proposed and investigated a super steep subthreshold slope transistor by introducing negative capacitance of a ferroelectric HfO2 gate insulator to a vertical tunnel FET for energy efficient computing. The channel structure and gate insulator are systematically designed to maximize the Ion/Ioff ratio. The simulation study reveals that the electric field at the tunnel junction can be effectively enhanced by potential amplification due to the negative capacitance. The enhanced electric field increases the band-to-band tunneling rate and Ion/Ioff ratio, which results in 10x higher energy efficiency than in tunnel FET.

TNANO Article in focus: January-February 2017

Thursday, March 16th, 2017

From the January 2017 issue of IEEE Transactions on Nanotechnology

Mechanical Properties Tunability of Three-Dimensional Polymeric Structures in Two-Photon Lithography

by Enrico Domenico Lemma; Francesco Rizzi; Tommaso Dattoma; Barbara Spagnolo; Leonardo Sileo; Antonio Qualtieri; Massimo De Vittorio; Ferruccio Pisanello
T-NANO, Vol. 16, Issue 1, pp. 23 – 31, January 2017.


Abstract: Two-photon (2P) lithography shows great potential for the fabrication of three-dimensional (3-D) micro- and nanomechanical elements, for applications ranging from microelectromechanical systems to tissue engineering, by virtue of its high resolution (<;100 nm) and biocompatibility of the photosensitive resists. However, there is a considerable lack of quantitative data on mechanical properties of materials for 2P lithography and of structures obtained through this technique. In this paper, we combined static and dynamic mechanical analysis on purpose-designed microstructures (microbending of pillar-like structures and picometer-sensitive laser Doppler vibrometry of drum-like structures) to viably and nondestructively estimate Young's modulus, Poisson's ratio, and density of materials for 2P lithography. This allowed us to analyze several polymeric photoresists, including acrylates and epoxy-based materials. The experiments reveal that the 2P exposure power is a key parameter to define the stiffness of the realized structures, with hyperelasticity clearly observable for high-power polymerization. In the linear elastic regime, some of the investigated materials are characterized by a quasi-linear dependence of Young's modulus on the used exposure power, a yet unknown behavior that adds a new degree of freedom to engineer complex 3-D micro- and nanomechanical elements.