bluuebunny/crossref_metadata_2025_split huggingface dataset:
(Invited) The Compact Models and Parameter Extraction for Thin Film Transistors
Authors: Shur Michael 
Published: February 2020

The challenge in the compact modeling of Thin Film Transistors (TFTs) is to accurately reproduce all regimes of operation (leakage, subthreshold, and above threshold) and account for short channel and non-ideal effects. The models should be suitable for the device characterization and parameter extraction. The non-ideal effects (which might be specific to a particular TFT type) include mobility degradation at high gate biases, velocity saturation (in poly-Si TFTs), drain-induced barrier lowering, self- heating, effects of the series resistance, and the floating-body effects. The self-heating and kink effects might become important in short channel devices [1]). The unified and universal charge control models [2] that describe both the above and below threshold characteristics with one generalized charge control equation are the basic FET models that have the advantages of a better convergence (avoiding the binning problem) and a relatively small number of parameters (simplifying the parameter extraction). These models have been augmented with the AC models that account for the RC constants represented by the fractions of the channel resistances in series with the gate-to-source and gate-to-drain capacitances for reproducing the frequency dispersion. The non-linear contacts have been modeled as non-linear transmission lines and/or non-ideal diodes. [3] Such compact TFT models have been implemented in circuit simulators [3] and, with certain modifications, they are suitable for the simulation of amorphous Si, poly-Si, monocrystalline silicon, and even organic TFTs. [4]
[1] L. Wang, T.A. Fjeldly, B. Iniguez, and M.S. Shur, Self-heating and Kink Effects in a-Si:H Thin Film Transistors, IEEE Trans. Electron Devices, Vol. 47, p. 387, February 2000
[2] T. A. Fjeldly, T. Ytterdal and M. Shur, `Introduction to device modeling and circuit simulation,' Wiley, NY 1997.
[3] B. Iniguez, L. Wang, Z. Xu, T.A. Fjeldly and M.S. Shur, Short Channel AIM-Spice Models for Amorphous and Polysilicon Thin Film Transistors, in Future Trends in Microelectronics. The Road Ahead, John Wiley and Sons, 1999, p. 213
[4] P.V. Necliudov, M.S. Shur, D.J. Gundlach, T.N. Jackson, Modeling of organic thin _lm transistors of different designs, J. Appl. Phys., December 15 (2000)

Figure 1
(Invited) Intrinsically-Stretchable, Transparent Thin Film Transistors
Authors: Tong Kwing , Liang Jiajie , Pei Qibing 
Published: February 2020

Thin-film field effect transistor (TFT) is a fundamental component behind morden electronic devices including displays, sensor arrays, microprocessers, and identification tags. Here, we report the development of new conductor, semiconductor, and dielectric materials that exhibit elastomeric deformability and solution processability. A silver nanowire based screen printing ik was formulaed to print silver nanowire electrodes with conductivity as high as 47K S/cm which are embedded in an elastomer matrix to preserve the electrical conductivity at large strains. A semiconductive single-walled carbon nanotube network was employed as the channel material, and a polyurethane-co-polyethylene oxide as elastomeric dielectric. Intrinsically stretchable TFTs were fabricated using these new electronic materials. The fabrication processes involved the preparation of the source, drain and gate electrodes, semiconductor layer, dielectric layer, and substrate by solution-based techniques under ambient conditions. The resulting devices exhibited a mobility of ~30 cm2V-1s-1, on/off ratio of 103-104, switching current >100 mA, transconducance >50 mS, and relatively low operating voltages. The devices could be stretched by up to 50% strain while retaining a high mobility >10 cm2V-1s-1. No significant loss in electrical property was observed after 500 cycles of repeated stretching to 20% strain. The TFTs were used to drive organic light-emitting diodes with brightness controllable from 0 cd/m2 (off) to 200 cd/m2 (a typical display brightness). The approach and results represent an important progress toward the development of stretchable active matrix displays and other stretchable electronic devices.
Oxide TFT with Sog Gate Insulator
Authors: Hwang Sang Ho , Hong Min-Taek , Lee Jong Mo , Jang Hee jin , Yun Eui Jung , Bae Byung Seong , Kim Myeong Seok , Huh Hyun Sue 
Published: February 2020

Oxide TFT (thin film transistor) shows higher mobility and less leakage current than amorphous silicon TFT. In this presentation, we investigated solution processed gate insulator for the oxide TFT. The solution process does not require the use of expensive vacuum equipment, and also has advantages of simple process, high productivity and low cost.
Less defects and trap centers are required for the gate insulator and the conventional material is SiO2 for which vacuum equipments are used to deposit it. Since the gate insulator is deposited on the active layer for the top gate structure, active layer can be deteriorated by plasma ion bombardment during deposition of the gate insulator.
Plasma damage exerted on the active layer during the deposition of the gate insulator have an adverse effect on the TFT characteristics. On the other hand, solution process does not use plasma, therefore, it can remove plasma damage on the active layer. And also, solution process is inexpensive and highly productive process.
In this experiments, we used spin on glass material for the solution process of the gate insulator. We investigated the effect of dilution of the SOG with IPA (isopropyl alcohol). It was coated on a p-type Si wafer by spin coating with 3500 rpm. For the diluted solution, we coated several times for the desired thickness of the gate insulator. Hard bake was done for 20 min at 170℃ after soft-bake for 20 min at 85℃. Final cure was done for 1 hour at 420℃ in nitrogen ambient. Figure 1 shows the current densities of the SOG insulator for the various dilutions of SOG solution. The leakage currents were reduced for the diluted solution.

Figure 1
Improved Properties of Oxide Thin-Film Transistor By Electrohydrodynamic-Jet Printing
Authors: Kwack Young-Jin , Choi Woon-Seop 
Published: February 2020

Oxide Semiconductors have been paid attention to suitable TFTs for OLED because of higher mobility than a-Si TFTs, lower leakage current than LTPS TFTs and even low cost. These oxide thin films can be obtained by simple solution process and applied to printed electronics. Printing process is a way to reduce cost and process time effectively over tranditional vacuum process and photo-lithography by direct patterning. Nevertheless, semiconductor films, in most study of solution processed oxide TFTs, are fabricated by spin coating, which is inadequate for electronics industry. For this reason, researches for various printing methodes on oxide TFTs are needed certainly. Electrohydrodynamic-jet(EHD-jet) technique is avilable to form a fine pattern by electric fields between metal stage and tiny orfice tip. We opimized EHD-jet printning conditions for ZTO solution and fabricated with addition patterning technique ZTO TFT sucessfully showing better and stable features than spin coated one.
The effects of speed and temperature of stage on printed pattern width was examined. As the stage temperature accelerated vaporization rate of solvent, printed pattern width was narrower and thicker. Thus, it is essential to optimize printing conditions for any solutions to obtain stable printing state. EHD-jet printed TFTs and patterned TFTs showed similar electrical characteristics with spin coated ZTO TFT but much improved contact resistance and leakage current. We investigated the origin of low leakage current based on the overlap of semiconductor with source and drain electrodes and related fringe effect. Electrical characteristic of ZTO TFT show a mobility of 6.9 cm2/Vs, an on-to-off current ratio of 4.7 x 108, a threshold voltage of 7V and a subthreshold-swing of 0.4 V/dec. Hysteresis behavior and passivation effect were also characterized.
Low Threshold Single Mode ZnO Nanowire Nanolasers
Authors: Visimberga Giuseppe , Boese Markus , O'Dwyer Colm 
Published: February 2020

With a wide bandgap of 3.36 eV at room temperature and large exciton binding energy of 60 meV (excitons being stable up to room temperature), ZnO holds promise for use in blue and ultraviolet optical devices [1], including ultraviolet microlasers. Lasing has been demonstrated with epitaxial and microcrystalline thin films [2], and in arrays of ZnO nanorods [3] and nanowires [4], for example. Usually, the feedback mechanism in nanorod and nanowire-based lasers is related to the formation of Fabry–Perot cavities for longitudinal modes [5], or to the structures ability to couple and facilitate guided modes [6]. Discriminating between the feedback mechanisms in ZnO nanostructures is not an easy issue, especially in microstructures consisting of nanorods with various orientations. Additionally, nanoscale systems also suffer from impure spectral characteristics and multimodal emission. Strategies to improve emission characteristics have seen limited success due to the sensitivity of nanoscale resonator cavities to optical properties dependant on structural shape and details of the crystallinity. Whispering gallery modes and complicated multimodal emission with a spread in gain factors compound the issue of spectrally pure emission in nanoscale systems.
High crystallinity is a prerequisite for short-cavity ZnO nanorod lasers due to expected coexistence of heavy mirror losses and scattering losses caused by the intrinsic structure and surface defects typically affecting ZnO. Here, arrays of vertically aligned ZnO nanorods were fabricated by CVD, with very high structural purity and quality. Characterization of aluminum deposition as surrounding layers on nanorods of 2-5 μm in length and 150-200 nm in width will be presented, and we detail the effect of selectively coated individual nanorods on the waveguiding and emission quality of the nanorod laser. The aluminum deposition alters the hexagonal cavity properties by reducing the guided modes and lowering the gain of the higher order modes so that a better, more spectrally pure emission is possible.
[1] U. Ozgur, Ya. I. Alivov, C. Liu, A. Teke, M. A. Reshchikov, S. Dogan, V. Avrutin, S.-J. Cho, M. Morkoc, J. Appl. Phys.
98, 041301 (2005).
[2] Z. K. Tang, G. K. L. Wong, P. Yu, M. Kawasaki, A. Ohtomo, H. Koinuma, Y. Segawa, Appl. Phys. Lett.
72, 3270 (1998).
[3] G. Visimberga, C. C. Faulkner, M. Boese and C. O'Dwyer, ECS Trans., 45, 51 (2012).
[4] S. P. Lau, H. Y. Yang, S. F. Yu, H. D. Li, M. Tanemura, T. Okita, H. Hatano, H. H. Hng, Appl. Phys. Lett.
87, 013104 (2005).
[5] Y. Zhang, R. E. Russo, S. S. Mao, Appl. Phys. Lett.
87, 043106 (2005).
[6] H. Zhou, M. Wissinger, J. Fallert, R. Hauschild, F. Stelzl, C. Klingshirn, H. Kalt, Appl. Phys. Lett.
91, 181112 (2007).
Self Assembled ZnO Nanowire Field Effect Transistors
Authors: Matei Elena , Florica Camelia , Costas Andrea , Enculescu Monica , Enculescu Ionut 
Published: February 2020

Electrodeposition of ZnO from aqueous baths may be employed as a straightforward path in obtaining in a cheap way nanostructures with well tailored morphology. Nanowires are a particular type of nanostructure which can be obtained in this way with or without employing a template. Further these nanowires can be employed as channel in field effect transistors. However the fabrication of such electronic devices based on nanowires is a difficult and time consuming task due to the challenge in providing the nanostructures with electrical contacts. Usually techniques such as electron beam lithography or focused ion beam induced metallization are employed for this goal [1].
We present here an alternative to these approaches in which simple electrodeposition on interdigitated electrodes can lead to the formation of high quality field effect transistors with pure or doped ZnO nanowire channel. The applications of such nanostructure based devices are numerous most being related to sensing applications where one makes use of the high surface to volume ratio and a cheap and easily scalable method of fabrication represents an important advantage.
References
[1] C. Florica, E. Matei, A. Costas, M.E.T. Molares, I. Enculescu, Field Effect Transistor with Electrodeposited ZnO Nanowire Channel, Electrochim. Acta. 137 (2014) 290–297. doi:10.1016/j.electacta.2014.05.124.
(Invited) Multi-Functional Flexible Healthcare Sesnors and Integrated Circuits
Authors: Takei Kuniharu 
Published: February 2020

The concepts of trillion sensor network and Internet of Things (IoT) require a variety of sensors that can be economically attached on any surfaces. To address this requirement, printed flexible electronics is one of solutions to integrate multifunctional macro-scale sensor networks without increasing fabrication cost compared to the Si-based sensors. To show a proof-of-concept of the printed and flexible devices, in this talk, a printed multi-functional flexible healthcare patch will be presented. The device contains a temperature sensor, a electrocardiogram sensor, an acceleration sensor, and an ultraviolet sensor on a flexible plastic substrate, which are fabricated by all printing methods. Especially, inorganic nanomaterials mixed with organic materials were used to achieve the high performance, air-stability, and mechanical flexibility. Furthermore, for the future flexible signal processing circuits, digital and analog circuits will be also demonstrated. It should be noted that those circuits are still fabricated by using a standard semiconductor lithography technique due to difficulity of material integration using printing methods. Those multi-fuctional sensors and flexible circuits are successfully demonstrated as the first proof-of-concepts. Although more developments to realize printed fully flexible device systems are required, we believe that the demonstrations of the macro-scale flexible sensor sheets may contribute to move forward to realizing the next generation electronics.
(Invited) Towards High-Power All-Solid-State Batteries
Authors: Kühnel Ruben-Simon , Duchêne Léo , Roedern Elsa , Remhof Arndt , Battaglia Corsin 
Published: February 2020

While the size of electronic components has shrunk dramatically over the last few decades, the footprint of autonomous electronic devices is today often limited by the battery. Miniaturization of batteries is challenging in particular when using liquid electrolytes based on organic solvents. All-solid-state batteries employing solid-state electrolytes promise to facilitate miniaturization and integration. Current developments of solid-state electrolytes for lithium ion batteries focus mainly on oxide- and thiophosphate-based compounds, but have not yet enabled the fabrication of a competitive all-solid-state battery.
We recently reported the discovery of a superionic phase at room temperature in the class of lithium amide-borohydrides, enabling ionic conductivities comparable to values of common organic liquid electrolytes. We demonstrate good rate performance up to 5C and stable cycling over 400 cycles at 1C in a lithium titanate half-cell battery configuration, indicating high bulk and interfacial stability. Our results demonstrate the potential of lithium amide-borohydrides as solid-state electrolytes for scalable high-power lithium ion batteries.
Effects of Asymmetric Local Joule Heating on Silicon Nanowire-Based Devices and Their Applications
Authors: Ho Hsiang-Hsi , Tsai Wei-Che , Hong Liang-Zheng , Lyu Cheng-Han , Chien Wen-Ching , Hsu Hsun-Feng 
Published: February 2020

With rapid advancement of semiconductor manufacturing and measurement techniques, silicon nanowires (Si NWs) have been produced by several methods and successfully incorporated in solar cells, light emitting diodes and photodetectors due to their unique properties, such as high surface-to-volume ratio, quantum confinement effect and high crystal quality.
In this study, silicon nanowires were fabricated by metal assisted–chemical etching (MacEtch) combined with nanosphere lithography (NSL) and subsequently used as building blocks for parallel silicon nanowire-based devices using alternating current (AC) or direct current (DC) dielectrophoresis alignment across Pt electrodes. The role of Si NWs/Pt metal contacts and its effect on electrical and photosensing properties of the devices were investigated.
The results show that the devices exhibited rectifying current-voltage characteristics randomly after the strong AC electric field was applied across electrodes for NWs alignment. On the other hand, the rectifying behavior of the devices can be observed as the devices were measured in the wide voltage range after the weak DC electric field was applied across electrodes for NWs alignment, and furthermore the rectification direction can be controlled by the voltage sweep direction. This phenomenon can be associated with the increased Schottky barrier height on the high-temperature anode side as the asymmetric Joule heating effect occurs instantly in the electrical measurement process.
The photosensing properties of the rectifying device were further investigated. By utilizing the increased Schottky barrier height in reverse-biased mode under white light illumination, the high speed and high photoresponse can be achieved due to the efficient electron-hole separation by strong built-in electric field in the depletion region.
The Novel Way to Inspection Technique for SiC Substrate by Applying Stress Effects
Authors: Sakata Yoshitaro , Terasaki Nao , Nonaka Kazuhiro 
Published: February 2020

Silicon carbide (SiC) has attracted much attention as an important material for high temperature, high power and high frequency devices, because it has advantages compared to silicon (Si) devices. However, SiC substrates are made the same way with Si substrates in production manufacturing.
In production site, fine polishing techniques, such as a chemical mechanical polishing treatment (CMP), are some of the most important base techniques used for the semiconductor manufacturing. Mechanical interaction in the form of friction occurs between the abrasive and the substrate surface during polishing, which may cause formation of latent flaws on the silicon carbide (SiC) substrate surface. Fine polishing-induced latent flaws may become obvious during a subsequent cleaning process if SiC substrates are corroded away by chemical interaction with the cleaning liquid. Latent flaws thus reduce product yield.
Recently, many nondestructive inspection systems that use light scattering from foreign matter particles for their detection have been made commercially available for use in production sites. These systems use laser incident light and a photo-detector (e.g. a photomultiplier tube) for detecting light scattering from foreign particles with high sensitivity. Inspection systems based on Rayleigh scattering and Mie scattering can detect particles smaller than the laser wavelength. However, these systems detect all light scattering as foreign matter particles on the surface. Therefore, these system cannot discriminate between latent flaws and particles. In addition, these inspection techniques cannot detect defects under the surface of substrates.
We propose a novel inspection technique for fine polishing-induced latent flaws by combining the light scattering method with stress effects, referred to as the stress-induced light scattering method (SILSM, Y. Sakata, et al, Review of Scientific Instruments, Vol. 85, No. 8, p. 083303-1 (2014)). In this method, samples are deformed by an actuator and stress effects are induced around the tips of latent flaws. Due to the photo elastic effect, the refractive index of the material around the tip of a latent flaw is changed. This changed refractive index is in turn detected by a cooled CCD camera as variations in the light scattering intensity.
In this report, latent flaws under the surface of SiC substrate are detected non-destructively by applying SILSM, and the utility of SILSM will be evaluated as a novel inspection technique for the substrate. In addition, the results detected by SILSM is compared with the results of conventional laser raman spectrometry and photo-luminescence results, respectively. And latent flaws under SiC substrate surface is evaluated from various directions.
This research was partially supported by AIST-AMRI budget for Exploratory Research and we gratefully acknowledged this budget with deepest appreciation.
Relation Between Current Density Distribution in Land-Channel Direction and Presence of Liquid Water in Proton Exchange Membrane Fuel Cell Flow Channel
Authors: Karani Jash , Shrivastava Udit N , Tajiri Kazuya 
Published: February 2020

Since most of the PEMFCs have land-channel geometry in their flow field, the distance between the flow channel to the catalyst layer is not uniform. The distance is longer from the flow channel to the catalyst layer under the land area than to the catalyst layer under the channel area. This difference causes the non-uniform current density in land-channel direction, and the distribution largely depends on the operating conditions. As the inlet gas humidity in the operating condition decreases, the trend in the current density distribution changes from high local current under the channel to relatively uniform, and to higher local current under the land (Figure 1). This trend is due to the combined effects of (1) non-uniform oxygen transport resistance, (2) non-uniform liquid water transport distance causing the local flooding under the land area at wet condition, and (3) the tendency of faster membrane dryout under the channel area at dry condition.
In order to investigate the distributions of various parameters in the land-channel direction, a small-scale segmented cell with about 300-micron resolution was developed by the authors’ group, and successfully measured the current and high-frequency resistance distribution in the land-channel direction. Distribution of oxygen transport resistance from the flow channel to the catalyst layer was also measured using limiting current technique.
In this study a new segmented cell is developed. Using the transparent cathode plate the behavior of liquid water in cathode flow channel can be observed, and simultaneously the current density distribution is measured in land-channel direction. With this cell the relation between the current density distribution in the land-channel direction and the presence of liquid water is investigated. First, it is studied that at what gas humidity and at what overall current density the liquid water starts emerging from the gas diffusion layer surface to the flow channel. This provides us the information about the dependency of the liquid water emergence location on the current density distribution is studied. Then, how the presence of liquid water in the flow channel changes the current distribution is studied.

Figure 1