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Highlights of TNANO
Early Access Papers (up to 13 Feb. 2015)
Early Access articles are new content made available in advance of the final electronic or print versions and result from IEEE’s Preprint or Rapid Post processes. Preprint articles are peer-reviewed but not fully edited. Rapid Post articles are peer-reviewed and edited but not paginated. Both these types of Early Access articles are fully citable from the moment they appear in IEEE Xplore.
1. Li, Y.; Chen, W. ; Lu, W. ; Jha, R. Read Challenges in Crossbar Memories with Nanoscale Bi-Directional Diodes and ReRAM Devices. IEEE Transactions on Nanotechnology, DOI:1109/TNANO.2015.2403772. (Date of Publication: 13 Feb. 2015)
This paper presents a simulation based study of the impact of nanoscale bidirectional diode reverse saturation current, junction capacitance, and crossbar coupling capacitances on the read operation of nanoscale ReRAM devices in 1Diode 1ReRAM crossbar memory architectures. Our results show that the maximum achievable crossbar memory density is a strong function of the diode reverse saturation current which governs the sneak current in steady-state read mode. For read operations with ultra-fast read voltage pulses, additional sneak-paths due to diode junction capacitances and line-to-line coupling capacitances in crossbar arrays come into the picture. This causes transient spike in the read current which can adversely affect the read energy and permissible read time. The overshoot in read current worsens as the size of crossbar arrays increases. The simulation studies presented here provides an in-depth understanding of these issues and its implications on resistive crossbar arrays.
2. Das, J.; Scott, K. ; Rajaram, S. ; Burgett, D. ; Bhanja, S. MRAM PUF: A Novel Geometry Based Magnetic PUF With Integrated CMOS. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2397951. (Date of Publication: 2 Feb. 2015)
This manuscript addresses a novel MRAM-based Physically Unclonable Function (PUF). The PUF responses are generated using the unique energy-tilt, which is an outcome of the random geometric variations in the MRAM cells. We have verified relevant attributes of this PUF through extensive magnetic simulations and in-house fabrication results. Our fabricated PUF cells generate entropy as high as 0.99, which is comparable to most of its competitors. To our knowledge, the footprint of the PUF cells is also lower than the majority of silicon PUFs. Also, the authentication control algorithm for this PUF requires very low additional control-steps. We conclude our discussion of this novel PUF with a study of authentication overhead and protocols required by the PUF system in terms of area, power and delay.
3. Szakmany, G.P.; Orlov, A.O. ; Bernstein, G.H. ; Porod, W. Novel Nanoscale Single-Metal Polarization-Sensitive Infrared Detectors. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2397861. (Date of Publication: 2 Feb. 2015)
We report a vastly simplified approach to infrared (IR) detection based on a single-metal nanostructure. This integrated structure contains a dipole antenna and a thermocouple (TC). The antenna provides wavelength selectivity, and the TC provides the conversion from optical to electrical signals. Moreover, the same nanowire structure serves both as the receiving element (antenna) and as the rectifying element (TC), yielding a highly integrated detector system. This work exploits a newly-discovered thermoelectric effect in single-metal nanostructures with cross-sectional discontinuities to effect the TC functionality. In order to optimize the IR response, devices with various antenna lengths are simulated and fabricated. Both simulations and experiments demonstrate that the locations of the hot and cold TC junctions reverse as the polarization of the incident IR radiation changes, which results in reversal of the output signal polarity. The fabrication complexity of these single-metal devices is greatly reduced compared to that of other IR detector approaches, and their unique polarization-dependent response makes them attractive for new classes of infrared systems.
4. Cabellos-Aparicio, A.; Llatser, I. ; Alarcon, E. ; Hsu, A. ; Palacios, T. Use of THz Photoconductive Sources to Characterize Tunable Graphene RF Plasmonic Antennas. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2398931. (Date of Publication: 2 Feb. 2015)
Graphene, owing to its ability to support plasmon polariton waves in the terahertz frequency range, enables the miniaturization and electrical tunability of antennas to allow wireless communications among nanosystems. One of the main challenges in the characterization and demonstration of graphene antennas is finding suitable terahertz sources to feed the antenna. This paper characterizes the performance of a graphene RF plasmonic antenna fed with a photoconductive source. The terahertz source is modeled and, by means of a full-wave EM solver, the radiated power as well as the tunable resonant frequency of the device is estimated with respect to material, laser illumination and antenna geometry parameters. The results show that with this setup, the antenna radiates terahertz pulses with an average power up to 1 μW and shows promising electrical frequency tunability.
5. Kim, M.; Moon, D. ; Yoo, S. ; Lee, S. ; Choi, Y. Investigation of physically unclonable functions using flash memory for integrated circuit authentication. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2397956 (Date of Publication: 2 Feb. 2015)
Flash memory devices are investigated to confirm their application as physically unclonable functions (PUFs). Inherent fluctuations in the characteristics of flash memory devices, even with identical fabrication processes, produce different outputs, which are useful for device fingerprints. A difference in programming/erasing efficiency arises from a widely distributed threshold voltage. However, statistical fluctuations in the threshold voltage represent an advantage for PUF applications. The characteristics of PUFs, such as their unclonability, uncontrollability, unpredictability, and robustness, are investigated using fabricated flash memory devices. A simulation study is performed to support the experimental results and to show that the unpredictability is induced by variations in the gate dielectric thickness.
6. Mothes, S.; Claus, M. ; Schroter, M. Towards linearity in Schottky barrier CNTFETs. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2397696 (Date of Publication: 30 Jan. 2015)
Carbon nanotube (CNT) field-effect transistors (FETs) are expected to be beneficial for analog high-frequency applications due to, among others, their inherent linearity and thus very low signal distortion. Achieving this linearity has so far been assumed to depend on meeting the following conditions: ballistic single-subband transport, ohmic contacts, and quantum capacitance limited operation1. However, these conditions are very difficult to meet in realistic devices and circuit applications. It is shown in this paper that high linearity is also possible under significantly relaxed and, in particular, more practical conditions. This paves the way towards the exploration of linearity in realistic devices suffering from carrier scattering in the channel and with Schottky-like contacts as well as thicker and lower- gate oxides, which do not allow operation in the quantum capacitance limit. This study is based on results obtained with a Boltzmann transport equation solver that includes tunneling through potential barriers.
7. Chua, M.; Chui, Chee-Kong. New Attenuation Predictive Model for Carbon-Based Nanocomposites. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2396536 (Date of Publication: 29 Jan. 2015)
The use of carbon nanofibers reinforced composites is popular among several industries such as healthcare, aerospace and defense as they have enhanced mechanical and thermal properties. Carbon Nano Fibers (CNF) and Carbon Nano Tubes (CNT) in the composites also improve damping and attenuation. We have been investigating its application for scaffold implants in human airways which undergoes vibratory stress and requires weight-sensitive sound proofing. This paper proposes a predictive model for the attenuation of sound waves through the composite that takes into consideration the Rayleigh scattering function, absorption, resonance and interfacial friction of the embedded fibers. These factors are dependent on the size, thickness, density, porosity, Young Modulus and volume fraction of the nanofibers or nanotubes. Carbon Nano Fibers Reinforced PDMS (CNFRP) and Single Walled Carbon Nano Tubes Reinforced Poly-di-methylsiloxane (SWCNTRP) composites were investigated. Ultrasonic testing and measurement of sound wave attenuations through the material were done to validate the proposed model and results are shown to be consistent.
8. Narang, R.; Saxena, M. ; Gupta, M. Comparative Analysis of Dielectric Modulated FET and TFET based Biosensor. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2396899 (Date of Publication: 29 Jan. 2015)
An extensive study is presented to describe the impact of partial hybridization on the device electrostatics and On current of a Silicon Dielectric Modulated Tunnel Field Effect Transistor (DM-TFET). To gain insight into the various design considerations and factors influencing the sensitivity, both process related issue such as cavity length variation and real time issues related to biomolecules behavior such as partial hybridization (PH), charge, and position of receptors/target molecules have been investigated through extensive numerical simulations. The results indicate that TFET based sensor does not suffer from scaling issues and thus can help in miniaturization without compromising the sensitivity, unlike a nanogap embedded DM-FET.
9. Salmani-Jelodar, M.; Mehrotra, S.R. ; Ilatikhameneh, H. ; Klimeck, G. Design Guidelines for Sub-12 nm Nanowire MOSFETs. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2395441 (Date of Publication: 26 Jan. 2015)
Traditional thinking assumes that a light effective mass (m), high mobility material will result in better transistor characteristics. However, sub-12 nm metal-oxide-semiconductor field effect transistors (MOSFETs) with light m may underperform compared to standard Si, as a result of source to drain (S/D) tunneling. An optimum heavier mass can decrease tunneling leakage current, and at the same time, improve gate to channel capacitance because of an increased quantum capacitance (Cq). A single band effective mass model has been used to provide the performance trends independent of material, orientation and strain. This paper provides guidelines for achieving optimum m for sub-12 nm nanowire down to channel length of 3 nm. Optimum m are found to range between 0.2 – 1.0 m0 and more interestingly, these masses can be engineered within Si for both ptype and n-type MOSFETs. m is no longer a material constant, but a geometry and strain dependent property of the channel material.
10. Yang, Y.; Mathew, J. ; Ottavi, M. ; Pontarelli, S. ; Pradhan, D. Novel Complementary Resistive Switch Crossbar Memory Write and Read Schemes. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2394450 (Date of Publication: 26 Jan. 2015)
Recent trends in emerging non-volatile memory systems necessitate efficient read/write (R/W) schemes. Efficient solutions with zero sneak path current, non destructive R/W operations, minimum area and low power are some of the key requirements. Towards this end, we propose a novel crossbar memory scheme using a configuration row of cells for assisting R/W operations. The proposed write scheme minimizes the overall power consumption compared to the previously proposed write schemes and reduces the state drift problem. We also propose two read schemes namely assisted-restoring and self-resetting read. In assisted-restoring scheme, we use the configuration cells which are used in the write scheme, whereas we implement additional circuitry for self-reset which addresses the problem of destructive read. Moreover, by formulating an analytical model of R/W operation, we compare the various schemes. The overhead for the proposed assisted-restoring write/read scheme is an extra redundant row for the given crossbar array. For a typical array size of 200 200 the area overhead is about 0:5%, however, there is a 4X improvement in power consumption compared to the recently proposed write schemes. Quantitative analysis of the proposed scheme is analyzed by using simulation and analytical models.
11. Zhao, Y. ; Zhang, Y. ; Wang, Q. ; Hu, H. Review on the optimization methods of slow light in photonic crystal waveguide. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2394410 (Date of Publication: 26 Jan. 2015)
Slow light in photonic crystal waveguide (PCW) is now being heavily investigated for applications in optical devices. However, slow light with high group index in perfect PCW is usually accompanied by large group velocity dispersion (GVD), which would severely limit the bandwidth of slow light, deform optical pulses, and disturb its practical applications. In this review, various optimization methods that are proposed to overcome these drawbacks are introduced and compared. These methods rely largely on the ability to modify the slow light properties of PCWs with a change in their structural parameters or a change in their effective refractive indices through external agents. For each optimization method, the corresponding group index, GVD, bandwidth, and normalized delay-bandwidth product are all presented along with the physical parameters, the potential advantages, and the fabrication complexity of PCW that enable them. Finally, the key problems and future development directions of slow light in PCW are discussed.
12. Vishnoi, R. ; Kumar, M.J. A Compact Analytical Model for the Drain Current of Gate All Around Nanowire Tunnel FET accurate from Sub-threshold to ON-state. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2395879 (Date of Publication: 22 Jan. 2015)
We present a compact analytical model for the drain current of a Gate-All-Around (GAA) Nanowire Tunneling Field Effect Transistor (TFET). The model takes into account the effect of oxide thickness, body doping, drain voltage and gate metal work function. The model uses a tangent line approximation method to integrate the tunneling generation rate in the source-body depletion region. The accuracy of the model is tested against three dimensional numerical simulations calibrated using experimental results. The model predicts the drain current accurately in both the ON-state (strong inversion) as well as in the sub-threshold region.
13. Yong, Y. ; Moheimani, S. Collocated Z-axis Control of a High-Speed Nanopositioner for Video-rate Atomic Force Microscopy. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2394327 (Date of Publication: 20 Jan. 2015)
A key hurdle to achieve video-rate atomic force microscopy (AFM) in constant-force contact mode is the inadequate bandwidth of the vertical feedback control loop. This paper describes techniques used to increase the vertical tracking bandwidth of a nanopositioner to a level that is sufficient for video-rate AFM. These techniques involve the combination of: a high-speed XYZ nanopositioner; a passive damping technique that cancels the inertial forces of the Z actuator which in turns eliminates the low 20-kHz vertical resonant mode of the nanopositioner; an active control technique that is used to augment damping to high vertical resonant modes at 60 kHz and above. The implementation of these techniques allows a tenfold increase in the vertical tracking bandwidth, from 2.3 kHz (without damping) to 28.1 kHz. This allows high-quality, video-rate AFM images to be captured at 10 frames/s without noticeable artifacts associated with vibrations and insufficient vertical tracking bandwidth.
14. Yeh, Wen-Kuan; Lin, Cheng-Li ; Chou, Tung-Huan ; Wu, K. ;Yuan, Jiann-Shiun. The Impact of Junction Doping Distribution on Device Performance Variability and Reliability for Fully Depleted Silicon on Insulator with Thin BOX Layer MOSFETs. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2394247 (Date of Publication: 20 Jan. 2015)
In this work, we investigate the impact of junction doping distribution (LDD/halo) on variations and asymmetry of device characteristics for Fully Depleted Silicon on Insulator (FDSOI) with ultrathin buried oxide (UTB) layer nMOSFET. The device performance and hot carrier induced degradations have also been examined. Junction doping dose of LDD/halo affects the effective channel length, parasitic source/drain resistance and channel mobility. High junction doping dose enhances the device’s performance but degrades device stability and reliability. Compared to high junction doping FDSOI nMOSFET, low junction doping device has lower device variability, better symmetry and reliability, but suffers lower channel mobility and device driving capability.
15. Chou, C. Impact of receiver reaction mechanisms on the performance of molecular communication networks. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2393866 (Date of Publication: 19 Jan. 2015)
Molecular communication networks can be used to realise communication between nano-scale devices. In a molecular communication network, transmitters and receivers communicate by using signalling molecules. At the receivers, the signalling molecules react, via a chain of chemical reactions, to produce output molecules. The counts of output molecules over time is the output signal of the receiver. The output signal is noisy due to the stochastic nature of diffusion and chemical reactions. This paper aims to characterise the properties of the output signal. We do this by modelling the transmission medium, transmitter and receiver. In order to simplify the analysis, we model the transmitter as a sequence which specifies the number of molecules emitted by the transmitter over time. This paper considers two receiver reaction mechanisms, reversible conversion and linear catalytic, which can be used to approximate, respectively, ligand-receptor binding and enzymatic reactions. These two mechanisms are chosen because, if we consider them on their own (i.e. without the transmitter and diffusion), the ordinary differential equations describing the mean behaviour of these two reaction mechanisms have the same form; however, if we consider the end-to-end behaviour from the transmitter signal to the mean/variance of the number of output molecules, then these two receiver reaction mechanisms have very different behaviours. We show this by deriving analytical expressions for the mean, variance and frequency properties of the number of output molecules of these two receiver reaction mechanisms. In addition, for reversible conversion, we are able to derive the exact probability distribution of the number of output molecules. Our model allows us to study the impact of design parameters on the communication performance. For example, we assume that our receiver is enclosed by a membrane and we study the impact of the diffusibility of molecules across this membrane on the communication – erformance.
16. Kuo, Hung-Fei; Wu, Wei-Chen. Forming Freeform Source Shapes by Utilizing Particle Swarm Optimization to Enhance Resolution in Extreme UV Nanolithography. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2393916 (Date of Publication: 19 Jan. 2015)
This research investigated pixel-based source shape optimization to enhance the resolution in a projection extreme UV (EUV) lithography system. The particle swarm optimization (PSO) method was proposed to optimize the source shapes. The layout patterns of the masks were corrected using model-based optical proximity correction. The optimal source shape in an EUV lithography system was verified using numerical calculations, through which the aerial image of two types of mask pattern exposure was determined. The two types of mask patterns were a logic line/space (L/S) pattern with a critical dimension (CD) of 16 nm and a SRAM contact hole (CH) pattern with a CD of 45 nm. Two significant metrics were used to evaluate the modified source performance: the latent image intensity and process window. Results from the numerical calculations showed that for L/S target patterns, using the optimal source produced a latent image error of 13.02% after exposure that was superior to that of traditional offaxis source exposure. The latent image intensity of the mask between the lines and the gaps differed substantially, corner rounding situations had effectively improved, and no bridges were observed. Concerning CH target patterns, using the optimal source produced a latent image error of 0.04% after exposure that was also superior to that of traditional sources. The latent image intensity between the holes and the gaps also differed significantly, and the latent image intensity distribution at the four corners of the contact holes had straight angles. Because the source shapes calculated in this study comprised pixel-based sources, the controllable microelectromechanical system (MEMS) mirror array chip was used to match each mirror to each pixel source, and the calculated source shapes were successfully projected.
17. Hwang, J.; Wang, F. ; Kung, C. ; Chan, M. Using the Surface Plasmon Resonance of Au Nanoparticles to Enhance Ultraviolet Response of ZnO Nanorods-Based Schottky-Barrier Photodetectors. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2393877 (Date of Publication: 19 Jan. 2015)
Surface plasmon resonance mediated by Gold (Au) nanoparticles (NPs) was employed to enhance the ultraviolet (UV) response of ZnO nanorod (NR)-based Schottky-barrier photodetectors (SB-PDs). The defect-level emissions of ZnO NRs induce surface plasmon resonance in Au NPs and enhance the electromagnetic field near Au NPs, which excites a great deal of electrons from Au NPs crossing over the barrier height of Au NP/ZnO interface. This causes the band-to-band emission of ZnO (384 nm) is increased by a magnitude of 3, and the deep-level emissions (450-700 nm) are drastically decreased as compared to ZnO NRs without coverings of Au NPs. Also it drastically enhance the UV (340 nm)-to-visible (560 nm) rejection ratio from 115 to 443. The effect of surface plasmon resonance is verified by that the responsivity of SB-PD with the covering of Au NPs exhibits a greater increasing with applied reverse-bias voltage than that without Au NPs.
18. Vargas Estevez, C.; Robaina, R.R. ; Perez del Real, R.P. ; Plaza, J.A. Nanometric metal-film thickness measurement
based on a planar spiral coils stack. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2392794 (Date of Publication: 15 Jan. 2015)
This work presents a sensor composed of a differential arrangement of coils capable of measuring nanometric metallic film thickness. Experimental results achieved aluminium thickness measurements as low as 20 nm with a sensitivity of 3.8 mV/nm. This makes this sensor a flexible, nondestructive and cheap alternative for metallic thickness measurement down to nanometric scale.
19. Hung, Shao-Kang; Cheng, Chiao-Hua ; Chen, Cheng-Lung. Automatic Patterned Sapphire Substrate Nanometrology Using Atomic Force Microscope. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2392128 (Date of Publication: 14 Jan. 2015)
Light emitting diodes become brighter because of the contribution of patterned sapphire substrates (PSS). The dimensions of PSS crucially affect its performance. The most suitable instrument to measure PSS is atomic force microscope, which provides three dimensional surface profiles. This paper proposes an automatic method to analyze AFM-collected raw data and produce characteristic parameters of PSS, including height, diameters, pitch, and side angles. Experimental results show that this method has good repeatability of 1.2 nm and 6.3 nm on measuring height and bottom diameter, respectively. This nanometrology method will be extensively applicable for similar nanostructures with periodic patterns.
20. Motaman, S.; Ghosh, S. ; Iyengar, A. Domain Wall Memory-Layout, Circuit and Synergistic Systems. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2391185 (Date of Publication: 12 Jan. 2015)
Domain wall memory (DWM) is gaining significant attention for embedded cache application due to low standby power, excellent retention and ability to store multiple bits per cell. Additionally, it provides fast access time, good endurance and retention. However, it suffers from poor write latency, shift latency, shift power and write power. DWM is sequential in nature and latency of read/write operations depends on the offset of the bit from the read/write head. This paper investigates the circuit design challenges such as bitcell layout, head positioning, utilization factor of the nanowire, shift power, shift latency and provides solutions to deal with these issues. A synergistic system is proposed by combining circuit techniques such as merged read/write heads (for compact layout), flipped-bitcell and shift gating (for shift power optimization), WL strapping (for access latency), shift circuit design with two micro-architectural techniques: 1) segmented cache, 2) workload-aware dynamic shift and write current boosting to realize energy-efficient and robust DWM cache. Simulations show 3-33% performance and 1.2X-14.4X power consumption improvement for cache segregation and 2.5-31% performance and 1.3X-14.9X power enhancement for dynamic current boosting over a wide range of PARSEC benchmarks.
21. Tewari, S.; Biswas, A. ; Mallik, A. Investigation on High Performance CMOS With p-Ge and n-InGaAs MOSFETs for Logic Applications. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2015.2390295 (Date of Publication: 9 Jan. 2015)
CMOS circuits built using Ge-channel p-MOSFETs and InGaAs-channel n-MOSFETs have shown promise for high performance logic applications. In this paper, we investigate for the first time the performance of such circuits using extensive device simulations. The digital performance of a CMOS inverter is evaluated in terms of noise margins, rise time, fall time and propagation delay. Furthermore, frequency of oscillations of a 3-stage ring oscillator is obtained for varying ratio of the channel width of the p- and the n- MOSFETs, respectively (Wp/Wn). Our investigations reveal that the CMOS circuits comprising of p-Ge and n-InGaAs MOSFETs outperform their equally-sized Si counterpart. Moreover, superior performance of Ge/InGaAs based CMOS is obtained for In0.75Ga0.25As channel with width ratio (Wp/Wn) of 10:1. Also, Ge/InGaAs CMOS is found to lose its advantages over Si CMOS for Dit exceeding 5×1012eV-1cm-2.
22. Wang, D. ; Zhao, W. ; Gu, X. ; Chen, W. ; Yin, W. Wideband Modeling of Graphene-based Structures at Different Temperatures Using Hybrid FDTD Method. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2387576 (Date of Publication: 5 Jan. 2015)
An efficient finite-
difference time-domain (FDTD) algorithm is proposed for studying frequency- and temperature-dependent characteristics of some graphene-based structures, with auxiliary differential equation (ADE)-FDTD method and its conformal modification technique integrated together for handling such atomically thin and electrically dispersive periodic geometries. Numerical results are presented to show their tunable transmittances, surface plasmon polarization (SPP)-mode characteristics and Fano Resonances, where the effects of chemical potential of graphene, biasing electric field strength as well as operating temperature are captured and investigated in detail.
23. Sahoo, M.; Ghosal, P. ; Rahaman, H. Modeling and Analysis of Crosstalk Induced Effects in Multiwalled Carbon Nanotube Bundle Interconnects: An ABCD Parameter Based Approach. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2388252 (Date of Publication: 1 Jan. 2015)
In this work, the crosstalk effects in both small and large diameter Multiwalled Carbon Nanotube bundle interconnects (MWCNTs) for the future nanoscale integrated circuits are studied with the help of ABCD parameter matrix approach for global levels of interconnects at 22 nm and 14 nm technology nodes. Here, isolated MWCNTs are modeled using an equivalent single conductor transmission line. The simulation results show that the results are at par with the result of SPICE model. It is observed that performance wise, the large diameter MWCNT bundles are better than both small diameter MWCNT bundles and copper wire for both repeated and unrepeated interconnects. The same trend is observed with the number of inserted repeaters. For repeated wires, the optimized placement of repeaters offset the delay advantage numbers of MWCNT bundles over copper wire. Technology scaling adversely impacts the delay advantage numbers of small diameter MWCNT bundles. As far as the worst case crosstalk noise peak voltage is concerned, the large diameter MWCNT bundles also outperform both small diameter MWCNT bundles and copper wire for longer interconnects. However, for shorter interconnects, copper wire and small diameter bundles outclass the large diameter bundles due to their relatively larger time constant. We have compared our crosstalk analysis results with the earlier work to justify the validity of our proposed model and observed that the results with our model are in well conformity with the existing work. It is seen that even the tall Cu vias are not going to significantly affect the performance of MWCNT bundle interconnects. Twice the minimum width global level interconnects are the optimal choice to achieve the maximum delay advantage using MWCNT bundle interconnects in comparison with Cu based interconnects. Finally, our analysis shows that from the performance and signal integrity perspective, the large diameter MWCNT bundles are a suitable alternative to both small diameter – WCNT bundles and copper interconnects for future Integrated circuit technology generations.
24. Xi, X.; Ma, Q. ; Dong, X. ; Wang, J. ; Yu, W. ; Liu, G. Flexible Janus Nanofiber to Help Achieve Simultaneous Enhanced Magnetism-Upconversion Luminescence Bifunction. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2385085 (Date of Publication: 31 Dec. 2014)
Novel flexible Janus nanofibers with magnetism-upconversion luminescence bifunction have been successfully fabricated via electrospinning technology using a homemade parallel spinneret. NaYF4:Yb3+,Er3+ and Fe3O4 nanoparticles (NPs) were respectively incorporated into polyvinyl pyrrolidone (PVP) and electrospun into Janus nanofibers with NaYF4:Yb3+,Er3+/PVP as one strand nanofiber of the Janus nanofiber and Fe3O4/PVP as the other one. The morphologies and properties of the final products were investigated in detail by X-ray diffractometry (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectrometry (EDS), vibrating sample magnetometry (VSM) and fluorescence spectroscopy. The results reveal that Janus nanofibers simultaneously possess superior magnetic and upconversion luminescent properties due to their special nanostructure, and the upconversion luminescent characteristics and saturation magnetizations of the Janus nanofibers can be tuned by adjusting the content of NaYF4:Yb3+,Er3+ NPs and Fe3O4 NPs. Compared with Fe3O4/NaYF4:Yb3+,Er3+/PVP composite nanofibers, the magnetism-upconversion luminescence bifunctional Janus nanofibers provide better performances owing to isolating NaYF4:Yb3+,Er3+ NPs from Fe3O4 NPs. The novel magnetism-upconversion luminescence bifunctional Janus nanofibers have potential applications in the fields of new nano-bio-label materials, drug target delivery materials and future nanodevices owing to their excellent magnetic-upconversion luminescent properties, flexibility and peculiar nanostructure. More importantly, the new strategy and construction technology are of universal significance to fabricate other bifunctional Janus nanofibers.
25. Jeon, J.; Jang, S. ; Jeon, S. ; Yoo, G. ; Park, J. ; Lee, S. Controlling grain size and continuous layer growth in two-dimensional MoS2 films for nano electronic device application. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2381667 (Date of Publication: 22 Dec. 2014)
We report that control over the grain size and lateral growth of monolayer MoS2 film, yielding a uniform large-area monolayer MoS2 film, can be achieved by submitting the SiO2 surfaces of the substrates to oxygen plasma treatment and modulating substrate temperature in chemical vapor deposition (CVD) process. Scanning electron microscopy and atomic force microscopy images and Raman spectra revealed that the MoS2 lateral growth could be controlled by the surface treatment conditions and process temperatures. Moreover, the obtained monolayer MoS2 films showed excellent scalable uniformity covering a centimeter-scale SiO2/Si substrates, which was confirmed with Raman and photo luminescence mapping studies. Transmission electron microscopy measurements revealed that the MoS2 film of the monolayer was largely single crystalline in nature. Back-gate field effect transistors based on a CVD-grown uniform monolayer MoS2 film showed a good current on/off ratio of ~106 and a field effect mobility of 7.23 cm2/Vs. Our new approach to growing MoS2 films is anticipated to advance studies of MoS2 or other transition metal dichalcogenide material growth mechanisms and to facilitate the mass production of uniform high-quality MoS2 films for the commercialization of a variety of applications.
26. Kesavan, A.; Ramamurthy, P. Effect of micro-structured copper as cathode material for P3HT based diode. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2380431 (Date of Publication: 22 Dec. 2014)
Here the effect of micro-structured cathode material on the device performance of indium tin oxide/poly(3- hexylethiophene)/copper diode (ITO/P3HT/Cu) is investigated. Two different forms of copper namely bulk metal (Cu{B}) and nano-particle (Cu{N}) were used as top electrode to probe its effect on device performance. Crystallographic structure and nanoscale morphology of top Cu electrodes were characterized using X-ray diffraction and scanning electron microscopy. Electrode formed by evaporation of copper nanoparticle showed enhancement in current density. From capacitance based spectroscopy we observed that density of trap states in ITO/P3HT/copper larger size grain (Cu-LG) are one order greater than that in ITO/P3HT/copper smaller size grain (Cu- SG) device.
27. Das, S. ; Pota, H. ; Petersen, I. A MIMO Double Resonant Controller Design for Nanopositioners. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2381274 (Date of Publication: 18 Dec. 2014)
A design of a double resonant controller to enhance the high speed nanopositioning performance of a piezoelectric tube scanner (PTS) is presented in this paper. The design of the controller is demonstrated using a multi-input multi-output (MIMO) framework for damping, tracking and cross coupling control in the PTS. A reference model c
ontrol technique is applied to design the controller. The controller proposed in the paper achieves a bandwidth near to the first resonance frequency of the PTS. The controller is robust against changes in the resonance frequency of the PTS due to load change on the scanner. Experimental results using open-loop, closed-loop and the built-in AFM proportional integral controller are presented to show the effectiveness of the proposed controller.
28. Zhang, R.; Zhao, W.-S. ; Hu, J. ; Yin, W.-Y. Electrothermal Characterization of Multilevel Cu-Graphene Heterogeneous Interconnects in the Presence of an Electrostatic Discharge (ESD). IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2381775 (Date of Publication: 18 Dec. 2014)
Temperature responses of multilevel Cu-graphene heterogeneous interconnects under the impact of an electrostatic discharge (ESD) are investigated by using our self-developed time-domain finite-element method (TD-FEM) algorithm. Corresponding to the advanced CMOS processes, all parameters of such multilevel interconnects are assessed by the ITRS. It is numerically shown that when capped with 10nm thick multilayer graphene, the maximum temperature of the Cu-graphene interconnect could be suppressed by 45% and 30% for 13.4 nm and 21 nm nodes, respectively. This study could be useful for improving the reliability of interconnects in the future nanoscale integrated circuits (ICs).
29. Fiorillo, A.; Tiriolo, R. ; Pullano, S.A. Absorption of Urea into zeolite layer integrated with microelectronic circuits. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2014.2378892 (Date of Publication: 12 Dec. 2014)
A simple and efficient technique allows the direct application of a mixture of zeolite 3A and castor oil onto surfaces, at low temperatures. This same technique can also be used to fabricate iono-electronic devices on silicon wafers for biomedical purposes. In this article, we investigate the use of a mixture of zeolite together with different vegetable oils aimed at obtaining thinner, more uniform, repeatable layers at even lower temperatures, which are capable of entrapping biological substances, specifically urea molecules. By choosing the proper mixture, the curing temperature can be optimized to make the process compatible with integrated circuit technology. A cold O2- plasma treatment was used during experimentation to activate the zeolite thin layer on silicon by removing the residual organic species. The absorption of urea molecules and its interaction with the zeolite framework was investigated through Fourier transform infrared spectroscopy.
30. Ramachandran, R.; Felix, S. ; Saranya, M. ; Santhosh, C. ;Ragupathy, B.P.C. ; Jeong, S. ; Grace, A.N. Synthesis of Cobalt sulfide-Graphene (CoS/G) nanocomposites for supercapacitor applications. IEEE Transactions on Nanotechnology, DOI: 1109/TNANO.2013.2274461 (Date of Publication: 21 Aug. 2013)
CoS and graphene nanocomposites was prepared from cobalt nitrate, thioacetamide and graphene as starting materials in the presence of poly(vinylpyrrolidone) as surfactant. Further its morphology and properties were characterized by X-ray diffraction (XRD), Field Emission scanning electron microscope (FESEM), Diffusive reflectance Ultraviolet–Visible spectroscopy (DRS-UV-Vis), Fourier Transform Infrared spectroscopy (FTIR) and electrochemical measurements. The XRD reveals the amorphous nature of the nanocomposites. The as prepared nanocomposites were tested for its supercapacitance property by cyclic voltammetric (CV) experiment in 6M KOH electrolyte.CV was performed at a potential range of 0 V to -0.8 V at different scan rates and results show an excellent capacitive behavior of the nanocomposites. A maximum specific capacitance of 2423.3 F/g was obtained at a scan rate of 5 mV/s.