IEEE Transactions on Nanotechnology
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Archive for the ‘Article in focus’ Category

TNANO Article in focus: May-June 2017

Thursday, June 15th, 2017

Article in Focus from the May 2017 issue of IEEE Transactions on Nanotechnology

 

Crossbar-Based Memristive Logic-in-Memory Architecture

by Georgios Papandroulidakis ; Ioannis Vourkas ; Angel Abusleme ; Georgios Ch. Sirakoulis ; Antonio Rubio
T-NANO, Vol. 16, Issue 3, pp. 491 – 501, May 2017.
 

Abstract: The use of memristors and resistive random access memory (ReRAM) technology to perform logic computations, has drawn considerable attention from researchers in recent years. However, the topological aspects of the underlying ReRAM architecture and its organization have received less attention, as the focus has mainly been on device-specific properties for functionally complete logic gates through conditional switching in ReRAM circuits. A careful investigation and optimization of the target geometry is thus highly desirable for the implementation of logic-in-memory architectures. In this paper, we propose a crossbar-based in-memory parallel processing system in which, through the heterogeneity of the resistive cross-point devices, we achieve local information processing in a state-of-the-art ReRAM crossbar architecture with vertical group-accessed transistors as cross-point selector devices. We primarily focus on the array organization, information storage, and processing flow, while proposing a novel geometry for the cross-point selection lines to mitigate current sneak-paths during an arbitrary number of possible parallel logic computations. We prove the proper functioning and potential capabilities of the proposed architecture through SPICE-level circuit simulations of half-adder and sum-of-products logic functions. We compare certain features of the proposed logic-in-memory approach with another work of the literature, and present an analysis of circuit resources, integration density, and logic computation parallelism.
 

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.

 
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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.
 


TNANO Article in focus: November 2016

Thursday, December 22nd, 2016

From the November 2016 issue of IEEE Transactions on Nanotechnology

Continuous Fabrication of Multiscale Compound Eyes Arrays With Antireflection and Hydrophobic Properties

by Linfa Peng; Chengpeng Zhang; Hao Wu; Peiyun Yi; Xinmin Lai; Jun Ni
T-NANO, Vol. 15, Issue 6, pp. 971 – 976, November 2016.

 
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Images of the multi-scale compound eyes arrays: (a) low magnification image of multi-scale compound eyes arrays, (b) close-up image of the single microlens and its surroundings, (c) AFM image of the ordered array of tapered pillars.

Abstract: The multiscale hierarchical structures inspired by moth’s compound eyes offer multifunctional properties in optoelectronic devices. However, it is still a major challenge to fabricate these hierarchical structures on large-area substrates using a simple and cost-effective technique. The roll-to-roll ultraviolet nanoimprint lithography (R2R UV-NIL) technique provides a solution for the continuous fabrication of multiscale compound eyes arrays due to its high-speed, large-area, high-resolution, and high-throughput. In this paper, the R2R UV-NIL technique was used to fabricate the multiscale compound eyes arrays on the PET substrate. The mold used in the R2R UV-NIL process was acquired by anodic aluminum oxide process and then the multiscale compound eyes arrays were directly obtained via one-step R2R imprinting. The obtained multiscale compound eyes arrays exhibit excellent antireflective performance within the wavelength 400-800 nm. Besides, the compound eyes arrays also equip the surface of the microlens with excellent hydrophobic characteristics. These multifunctional properties enable the multiscale compound eyes arrays to retain their superior optical properties in real-time environmental conditions. This report can provide a beneficial direction for the continuous production and widespread applications of the multiscale compound eyes arrays.
 


TNANO Article in focus: October 2016

Wednesday, October 19th, 2016

From the September 2016 issue of IEEE Transactions on Nanotechnology

Halloysite Clay Nanotubes as Carriers for Curcumin: Characterization and Application

by Chiara Dionisi ; Nemany Hanafy ; Concetta Nobile ; Maria Luisa De Giorgi ; Ross Rinaldi ; Sergio Casciaro ; Yuri M. Lvov ; Stefano Leporatti
T-NANO, Vol. 15, Issue 5, pp. 720 – 724, September 2016.

 
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Abstract: Halloysite is a nanostructured clay mineral with hollow tubular structure, which has recently found an important role as delivery system for drugs or other active molecules. One of these is curcumin, main constituent in the rhizome of the plant Curcuma Longa, with a series of useful pharmacological activities, hindered by its poor bioavalaibility and solubility in water. In this study, Halloysite clay nanotubes (HNTs) were characterized in terms of both structure and biocompatibility and they were used for curcumin delivery to cancer cells. The performed 3-(4, 5-dimethythiazol-2-yl)-2, 5-diphenyl-tetrazolium bromide (MTT) assay showed that HNTs have a high biocompatibility, also when coated with polymers, while curcumin is highly toxic for cancer cells. The release kinetics of curcumin from HNTs was investigated by the dialysis bag method, showing a slow and constant release of the drug, which can be further controlled by adding layers of polyelectrolytes to the external surface of the tubes. Successful polymer coating was followed by Zeta potential. The Trypan Blue assay showed a cytotoxic effect of loaded HNTs, proportional to the concentration of tubes and the incubation time. Successful HNTs uptake by breast cancer cells was demonstrated by Confocal Laser Scanning Microscopy images. All results indicate that HNTs are a promising carriers for polyphenol delivery and release.
 


TNANO Article in focus: September 2016

Thursday, September 8th, 2016

From the September 2016 issue of IEEE Transactions on Nanotechnology

Methodology and Design of a Massively Parallel Memristive Stateful IMPLY Logic-Based Reconfigurable Architecture

by YYasunao Katayama; Toshiyuki Yamane; Daiju Nakano; Ryosho Nakane; Gouhei Tanaka
T-NANO, Vol. 15, Issue 5, pp. 762 – 769, September 2016.

 
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Abstract: We present a framework of wave-based neuromorphic computing aiming at brain-like capabilities and efficiencies with nanoscale device integration. We take advantage of the unique nature of elastic nondissipative wave dynamics in both computations and IO communications in between as a means to natively implement and execute neuromorphic computing functions such as weighted sum in a spatiotemporal manner. Lower bound analysis based on a memory model and wave group velocity scaling is provided for conceptual evaluations.
 

TNANO Article in focus: August 2016

Thursday, September 8th, 2016

From the July 2016 issue of IEEE Transactions on Nanotechnology

Methodology and Design of a Massively Parallel Memristive Stateful IMPLY Logic-Based Reconfigurable Architecture

by Kamela C. Rahman; Dan Hammerstrom; Yiwei Li; Hongyan Castagnaro; Marek A. Perkowski
T-NANO, Vol. 15, Issue 4, pp. 675 – 686, July 2016.

 
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Abstract: Continued dimensional scaling of CMOS processes is approaching fundamental limits and, therefore, alternate new devices and microarchitectures are explored to address the growing need of area scaling and performance gain. New nanotechnologies, such as memristors, emerge. Memristors can be used to perform stateful logic with nanowire crossbars, which allows for implementation of very large binary networks. This paper involves the design of a memristor-based massively parallel datapath for various applications, specifically single instruction multiple data and parallel pipelines. The innovation of our approach is that the datapath design is based on space-time diagrams that use stateful IMPLY gates built from binary memristors. The paper also develops a new model and methodology to design massively parallel memristor-CMOS hybrid datapath architectures at a system level. This methodology is based on an innovative concept of two interacting subsystems: 1) a controller composed of a memristive RAM, MsRAM, to act as a pulse generator, along with a finite-state machine realized in CMOS, a CMOS counter, CMOS multiplexers, and CMOS decoders; 2) massively parallel pipelined datapath realized with a new variant of a CMOL-like nanowire crossbar array, memristive stateful CMOL with binary stateful memristor-based IMPLY gates. In contrast to previous memristor-based FPGA, our proposed memristive stateful logic field programmable gate array uses memristors for both memory and combinational logic implementation. With a regular structure of square abutting blocks of memristive nanowire crossbars and their short connections, our architecture is highly reconfigurable. We present the design of a pipelined Euclidean distance processor along with its various applications. Euclidean distance calculation is widely used by many neural network and similar algorithms.

 

TNANO Article in focus: July 2016

Tuesday, July 26th, 2016

From the July 2016 issue of IEEE Transactions on Nanotechnology

Effect of a Clock System on Bis-Ferrocene Molecular QCA

by Ruiyu Wang, Azzurra Pulimeno, Massimo Ruo Roch, Giovanna Turvani, Gianluca Piccinini, Mariagrazia Graziano
T-NANO, Vol. 15, Issue 4, pp. 574 – 582, July 2016.

 
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Abstract: Molecular quantum-dot cellular automata (mQCA) is found to be the most promising among all emerging technologies. It is expected to show remarkable operating frequencies (THz), high device densities, noncryogenic working temperature, and reduced power consumption. The computation relies on a new paradigm based on the interaction between nearby molecular QCA cells. This computation requires the aid of an external signal normally referred to as clock that enables/inhibits the molecular activity. The influence of clock on realistic molecules has never been deeply studied. In this paper, we performed a thorough analysis of the clock signal added to the molecular QCA cell based on an ad hoc synthesized bisferrocene molecule. Ab-initio simulations and further postprocessing of data have been used for characterizing the performance of bisferrocene molecule under the influence of a clock signal. Quantitative results on the molecule in terms of newly defined figures of merits, i.e., aggregated charge , equivalent voltage, and Vin-Vout transcharacteristic have been shown. Meanwhile, we demonstrate when and how much the presence of clock signal enhances or hinders the interactions between QCA molecules. These unprecedented data give a fundamental improvement to the knowledge on how information can be propagated through QCA devices. The results suggest directions to chemists, technologists, and engineers on how to proceed in the next steps for this promising technology.

 

TNANO Article in focus: June 2016

Wednesday, June 8th, 2016

From the May 2016 issue of IEEE Transactions on Nanotechnology

Smart Detector Cell: A Scalable All-Spin Circuit for Low Power Non-Boolean Pattern Recognition

by Hamidreza Aghasi ; Rouhollah Mousavi Iraei ; Azad Naeemi ; Ehsan Afshari
T-NANO, Vol. 15, Issue 3, pp. 356 – 366, May 2016.

 

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Abstract: We present a new circuit for non-Boolean recognition of binary images. Employing all-spin logic (ASL) devices, logic comparators and non-Boolean decision blocks for compact and efficient computation are designed. By manipulation of fan-in number in different stages of the circuit, the structure can be extended for larger training sets or larger images. Operating based on the main similarity idea, the system is capable of constructing a mean image and compare it with a separate input image within a short decision time. Taking advantage of the nonvolatility of ASL devices, the proposed circuit is capable of hybrid memory/logic operation. Compared with the existing CMOS pattern recognition circuits, this paper achieves a smaller footprint, lower power consumption, faster decision time, and a lower operational voltage.

 

TNANO Article in focus: May 2016

Tuesday, May 10th, 2016

From the May 2016 issue of IEEE Transactions on Nanotechnology

Printable Parallel Arrays of Si Nanowire Schottky-Barrier-FETs With Tunable Polarity for Complementary Logic

by Sebastian Pregl; AndrĂ© Heinzig; Larysa Baraban; Gianaurelio Cuniberti; Thomas Mikolajick; Walter M. Weber T-NANO, Vol. 15, Issue 3, pp. 549 – 556, May 2016.

 

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Abstract: In this paper, we present a novel technology of printable bottom-up grown Si nanowire parallel arrays for low-dissipation power electronics. Parallel aligned layers of monocrystalline Si nanowires can be deposited on arbitrary substrates over large areas by the printing process. The presented transistors consist of parallel arrays of longitudinal NiSi2-Si-NiSi2 nanowire heterostructures, which naturally show ambipolar transistor behavior when a single gate is employed. By a double gate architecture, a reconfigurable transitor component is created, for which unipolar p- or n-type characteristics can be obtained depending on the polarity of the second gate. Transfer and output characteristics of these transistors on a Si/SiO2 substrate with back gate, top gate, and reconfigurable double gate architecture are presented here in detail. Very high on/off-current ratios of over 108 are achieved with very low off-currents. Due to the high number of nanowires incorporated into individual parallel arrays, output currents of 0.5 mA and a high yield of functional transistors of close to 100% at nanowire coated areas are demonstrated.