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Electromagnetic (EM) wave emissions from wearable or flexible smart display devices can cause product malfunction and have a detrimental effect on human health. Therefore, EM shielding strategies are becoming increasingly necessary. Consequently, herein, we prepared a transparent acrylic polymer-coated/reduced graphene oxide/silver nanowire (Ag NW) (A/RGO/SANW) EM interference (EMI) shielding film via liquid-to-vapor pressure-assisted wet sintering. The film exhibited enhanced Ag NW network formation and antireflection (AR) effects. The wet-sintered Ag NW shielding film had a threshold radius of curvature (ROC) of 0.31 mm at a film thickness of 100 μm, demonstrating its high flexibility, whereas the conventional indium tin oxide (ITO) shielding film had a threshold ROC of ∼5 mm. The EMI shielding effectiveness (SE) of the A/RGO/SANW multilayer film was approximately twice that of the ITO film at a similar relative transmittance (84–85%). The optical relative reflectance of the Ag NW layer was reduced due to the AR effect, and the visible-light transmittance was considerably improved owing to the different refractive indices in the multilayer shielding film. Because the acrylic coating layer had a high contact angle, the multilayer film exhibited high temperature and humidity durability with little change in the SE over 500 h at 85 °C and 85% relative humidity. The multilayer film comprising wet-sintered Ag NW exhibited high flexibility and humidity durability, high shielding performance (more than 24 dB at a relative transmittance of 85% or more), and high mass productivity, making it highly applicable for use as a transparent shielding material for future flexible devices.

In the current study, dual‐active layer amorphous indium‐gallium‐zinc‐oxide (a‐IGZO) TFT has been fabricated by sequential deposition of oxygen‐rich layer on a top of oxygen‐poor layer in the active layer through oxygen partial pressure control in order to improve reliability under negative bias illumination stress (NBIS) condition. The method is very simple as it is performed in situwithout any post treatment. Reliability of a TFT that had a thickness of oxygen‐poor layer and oxygen‐rich active layer in the ratio of 6:4, quite improved with the threshold voltage shift Δof a‐IGZO TFT at around 3.2 V under NBIS condition of 1000 s in comparison with a TFT (8.5 V) that comprised only oxygen‐poor active layer. The increased reliability is attributed to decrease interaction with ambient and the reduction in the total neutral oxygen vacancy concentration due to the oxygen rich layer at the back‐channel region, which was confirmed by X‐ray photoelectron spectroscopy (XPS) analysis.

One-dimensional (1-D) SnO2lines as a representative semiconducting oxide were formed by using electrohydrodynamic (EHD) jet-printing of a tin chloride pentahydrate and polyvinylpyrrolidone (PVP, 1,200k, Aldrich) solution ink. The 1-D polymer lines, including Sn precursors, were created by controlling the viscosity, that is, the polymer/tin precursor ratio, and by adjusting printing conditions such as the tip-to-substrate distance, the applied voltage, the flow rate of ink and its velocity. The printed lines were dried at 200 °C to get rid of solvent and were finally heat-treated at 600 °C to burn out PVP and form a tin oxide line. We found that the linearity and the shape of the aligned 1-D SnO2could be controlled by adjusting various parameters such as the viscosity of the precursor solution, the ratio of Sn to the PVP polymer in the solution, the shape of the cone, the size of a droplet, the applied voltage, the working distance, and the flow rate on glass slides and Si wafers with a SiO2layer. We found that the heat treatment for removal of the polymers should be tailored to produce continuous 1-D SnO2lines due to the drastic volume reduction (> 90%) of the aligned fibers during the annealing process. The electrical and the NO-gas-sensing properties of the 1-D SnO2aligned on Si wafers with Au electrode patterns were evaluated.

A Pb-free PTC (positive temperature coefficient thermistor) heater was developed in the Ba0.97(Bi0.5Na0.5)0.03TiO3system especially for automotive part applications. The reliability was verified by using a thermal cycling test designed on the basis of the result from a quality function deployment (QFD) analysis. We compared the thermal cycling test results from the newly-developed Pb-free PTC heaters with the results from PTC heaters currently on the market, namely, PTC heaters containing Pb. Life prediction and stress-strength relationships were analyzed together with a thermal diffusivity evaluation. We discuss the potential failure mechanisms during the thermal cycling test, focusing on the fact that electrical degradation in PTC materials is closely related to mechanical degradation due to the internal stress in the materials that comes from repeated phase changes. Different grain size distributions on the sintered bulks were considered to a key factor for explaining the different results of the reliability tests between the new Pb-free PTC heaters developed in this study and the commercial PTC heaters containing Pb.

The photochemical tunability of the charge-transport mechanism in metal-oxide semiconductors is of great interest since it may offer a facile but effective semiconductor-to-metal transition, which results from photochemically modified electronic structures for various oxide-based device applications. This might provide a feasible hydrogen (H)-radical doping to realize the effectively H-doped metal oxides, which has not been achieved by thermal and ion-implantation technique in a reliable and controllable way. In this study, we report a photochemical conversion of InGaZnO (IGZO) semiconductor to a transparent conductor via hydrogen doping to the local nanocrystallites formed at the IGZO/glass interface at room temperature. In contrast to thermal or ionic hydrogen doping, ultraviolet exposure of the IGZO surface promotes a photochemical reaction with H radical incorporation to surface metal–OH layer formation and bulk H-doping which acts as a tunable and stable highly doped n-type doping channel and turns IGZO to a transparent conductor. This results in the total conversion of carrier conduction property to the level of metallic conduction with sheet resistance of ∼16 Ω/□, room temperature Hall mobility of 11.8 cm2V–1sec–1, the carrier concentration at ∼1020cm–3without any loss of optical transparency. We demonstrated successful applications of photochemically highly n-doped metal oxide via optical dose control to transparent conductor with excellent chemical and optical doping stability.

In recent, research about the oxide semiconductor based photo sensor such as photosensitive oxide TFTs and diodes has been emphasized. In this study, we report a new photosensitive a‐IGZO diode for photo sensor in interactive display. The diode has high on/off ratio and low leakage current density of ~10‐9A/cm2. Also, the diode has a great photosensitivity of ~107and ~104at reverse bias under ultra‐violet (UV) and visible light conditions, respectively.

Glass frits are used widely in the VFD, PDP, LCD, and OLED displays, solar cells, and automobiles. It is essential for glass frits to exhibit material properties such as low melting temperatures and coefficient of thermal expansion close to glass to prevent thermal shock and to lower the thermal stress. Glass frit containing 60%–85% of PbO lowers the melting temperature. However, PbO causes environmental pollution. In this study, we developed P2O5-SnO2-B2O3glass frits and carried out life tests on these systems. In addition, life tests were also carried out on Pb-containing glass frits (VFD) for comparison to predict the life of the P2O5-SnO2-B2O3systems. Subsequently, the failure mechanisms of VFD and Pb-free P2O5-SnO2-B2O3glass frits were analyzed.

Abstract: Thermoelectric cooling module (TEM) which is electric device has a mechanical stress because of temperature gradient in itself. It means that structure of TEM is vulnerable in an aspect of reliability but research on reliability of TEM was not performed a lot. Recently, the more the utilization of thermoelectric cooling devices grows, the more the needs for life prediction and improvement are increasing. In this paper, we investigated life distribution, shape parameter of the TEM through accelerated life test (ALT). And we discussed about how to enhance life of TEM through the Physics-of-failure. Experimental results of ALT showed that the thermoelectric cooling module follows the Weibull distribution, shape parameter of which is 3.6. The acceleration model is coffin Coffin-Manson and material constant is 1.8.

Abstract: The etch characteristics of high-k dielectric HfO2 films and the etch selectivity for HfO2 over Si in fluorine-and chlorine-based inductively coupled plasmas have been studied. Fluorine-based ICP discharges produced practical and controllable etch rates and the etched HfO2 surfaces sustained similar or better RMS roughness values than that of the unetched control sample under most of the conditions examined. Anisotropic pattern transfer with a vertical sidewall profile (θ = 97°) was performed in CF4/Ar ICP discharges and no significant change in the dielectric property of HfO2 films was detected. 5Cl2/10O2 ICP discharges produced high etch selectivities > 6.3 (max. ∼7.6) for HfO2 over Si.

This paper describes examines the non-linearity of multilayer ceramic capacitors (MLCC) with new equivalent circuits. The electric charge quantity (Q) was measured as a function of applied voltage (V) under 16 V ac-field to validate the ferroelectricity of MLCC with capacitance of 1 μF. The Q-V curves predicted under ac-field using B2 spice software showed the non-linearity of ferroelectricity in the high ac-field. The Q-V curve predictions were in agreement with the experimental data for the MLCC.

Electrochromic WO3 thin film was prepared by using tungsten metal solution in hydrogen peroxide as a starting solution and by a sol-gel dip coating method. The thermal analysis was conducted by DSC/TG method. A DSC/TG analysis and the XRD patterns showed that a tungsten oxide crystal phase was formed at 400oC. WO3 thin film when heat-treated at 300oC was amorphous and had a better electrochemical property than that of the crystalline phase. Crystallization of tungsten oxide decreased active sites of ion intercalation so that the current density decreased with heat-treatment temperature.

Electrochromic WO3 thin film was prepared by using tungsten metal solution in hydrogen peroxide as a starting solution and by sol-gel dip coating method. XRD pattern showed that tungsten oxide crystal phase formed at 400[removed info]. In the view of electrochemical property, WO3 thin film which was heat-treated at 300[removed info] and was amorphous had better than that of the crystalline phase.

In field aided lateral crystallization process which is one of the low temperature crystallization processes for the amorphous silicon films, the effect of the alternating field (AC voltage) instead of the static field (DC voltage) was investigated. Following the deposition of 2 nm thick Cu catalyst outside of the 5 mm bar patterns in the PECVD amorphous silicon film, the specimen was heated at 500℃ in N₂ambient for 5 hours with applying 5 V/cm AC-field along with 30 V/cm DC-field. As compared to the case of 35 V/cm DC-field only, the specimen from both the 30 V/cm DC and 5 V/cm AC resulted in 1.5 times faster crystallization velocity, regardless of the experimental frequency ranges of 100 Hz ~ 50 MHz. Presumably, the enhancement of the crystallization velocity under the combined field is associated with the increase in the flux of the crucial diffusion species, Cu atoms, which govern the overall crystallization velocity due to the agitation effect by the AC-field.

Considering practical application of field aided lateral crystallization process in channel region of thin film transistors, there might be a different crystallization behavior dependent on the shape of channel to be crystallized. In this study, channel array with various aspect ratios was prepared and the Cu field aided lateral crystallization process was carried out at 500ı for 10 hours with applying 30V/200㎛ through common electrodes for the sake of the actual channel area crystallization. Both the fraction of crystallized area and the degree of crystallization increase as the aspect ratio of channel become away from 1.

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(Ba,Sr)RuO 3 films have been tailored as an electrode for (Ba,Sr)TiO 3 which is a promising material for the high dielectric in ULSI DRAM. In this study, BSR conductive oxide film was deposited on 4-inch Si-wafer by metal organic chemical vapor deposition (MOCVD) using single cocktail source for the practical device application. Liquid delivery system (LDS) and vaporization cell were utilized for the delivery and vaporization of single cocktail source, respectively. The source feeding rate was controlled by liquid mass flow controller(LMFC). Ba(METHD) 2 , Sr(METHD) 2 , Ru(METHD) 3 precursors and solvent [n-butylacetate(C 6 H 12 O 2 )] were mixed for single coctail source. Among the various deposition parameters, control of the oxygen flow rate turned out to be crucial for determining the phase formation, resistivity, and the composition ratio of (Ba,Sr)RuO 3 films. Highly (110)-textured (Ba,Sr)RuO 3 film was obtained when Ar/O 2 ratio was 100/300sccm with the source flow rate of 0.075sccm. Oxygen annealing of (Ba,Sr)RuO 3 films enhanced the properties of the films without changing the (110) texture, and the resistivity of the resulted film was 2440 w z cm.

Effects of component layer thickness variation in 3-layer structure (TiO2/Pb/TiO2) on the phase formation and dielectric properties in PbTiO3 films were investigated. Multilayer films of total thickness of 1000 Å were grown on Si substrate by RF sputtering at room temperature and RTA(Rapid Thermal Annealing) process followed in order to form PbTiO3 by thermal diffusion. PbTiO3 phase begins to form at 500°C. Unreacted TiO2 and pyrochlore phase decrease as the content of Pb in the film increases. Reaction at the interface between film and substrate is slightly dependent on the component layer thickness variation and the morphology of interface is relatively sharp compared to the films grown by conventional processing. Relative dielectric constant is linearly proportional to the Pb content in the films. Crater shape defects on the surface were generated during RTA

The effects of hydrogen incorporation in the active layer of amorphous InGaZnO (a‐IGZO) thin‐film transistors (TFTs) on device characteristics and instability under positive bias stress (PBS) and positive bias temperature stress (PBTS) are studied. To control the amount of incorporated hydrogen, rapid thermal annealing (RTA) treatment is conducted on the gate insulator layer before active layer deposition. It is confirmed that the amount of residual hydrogen in the gate insulator layer decreases with increasing RTA treatment time. Device stability is examined with RTA treatment times of 1 and 3 min under PBS. The device fabricated with a shorter RTA treatment time shows relatively better stability. This result is attributed to defect passivation by hydrogen that diffuses to the active layer from the gate insulator during the post‐annealing process. Additionally, TFT shows the negative shift of Vthunder a high‐temperature PBTS condition. This result is due to the additional diffusion of residual hydrogen from the gate insulator into the active layer and hydrogen‐related deep state transition in the active layer by external thermal energy and a PBS condition. The effect of hydrogen on the device stability of amorphous InGaZnO (a‐IGZO) thin‐film transistors (TFTs) under positive bias with various temperature stresses is explained.

We fabricated self-aligned coplanar amorphous indium-gallium-zinc-oxide (a-IGZO) TFTs and defined the source/drain region using deep ultraviolet (DUV) irradiation. For our TFTs, source/drain region were well defined to designed dimensions and contact resistance was low value. The electrical properties of the device show field-effect mobility (μFE) of 13.2 cm2/Vs, subthreshold swing (S/S) of 0.32 V/decade, threshold voltage (Vth) of 3.2 V, and on/off ratio of 8.8 × 108, respectively. In addition, the reduced channel length (ΔL) and width-normalized contact resistance (RSDW) were 1.08 μm and 87.5 Ω cm, respectively. Stability behavior of self-aligned coplanar a-IGZO TFT fabricated by DUV irradiation was investigated under negative bias stress (NBS), negative bias illumination stress (NBIS), positive bias stress (PBS), and positive bias temperature stress (PBTS). After the stress under NBS, NBIS, PBS, and PBTS, the Δ Vthvalues of −0.3 V, −0.8 V, 1.2 V, and 1.3 V were measured, respectively. Additionally, the electrical characteristics of the n+ doping region by DUV irradiation were not degraded under any of the stress conditions.

We report on the facile synthesis of highly conductive RuO2/Mn3O4composite nanofiber mats by electrospinning of mixed ruthenium and manganese precurosr solution and their potential suitability as an active electrode in electrochemical capacitors. Electrospun RuO2/Mn3O4fiber mats calcined at 300°C exhibit multiple fiber networks composed of nanoparticles in a size range of 5–10 nm (average ≈ 7.5 nm). Partially crystalline Mn3O4phases are well mixed with the amorphous RuOx(a-RuO2) phases while pure Mn3O4fibers exhibit only crystalline phase. Electrochemical capacitors utilizing a-RuO2/Mn3O4fiber mats show a high specific capacitance of 293 Fg−1at 10 mVs−1, high rate capability with a capacity loss of only 45% from 10 to 2000 mVs−1, and superior cycle performance of over 30,000 cycles as compared to those characteristics of Mn3O4fiber mats (216 Fg−1at 10 mVs−1, capacity loss of 94% at 2000 mVs−1, poor cycle performance of 2000 cycles). These results are correlated with the improved mixed ionic/electronic conductivity of the a-RuO2/Mn3O4fiber mats as well as to its morphological evolution, i.e., highly porous flower-like-fiber networks, during cycling tests.

In order to reduce the leakage current in n-channel polycrystalline silicon thin film transistors processed by field-aided lateral crystallization, we applied a reduced gate structure that enables an offset region between the channel and source-drain. The structure in this study was much simpler than those of other methods in the sense that it could accomplish both offset-gate and Ni-offset effects simultaneously without employing any additional masks or processes. The leakage current decreased as the offset region length ΔL per side increased. When ΔL = 2 μm, which corresponded to 10 percent of the total channel length of L = 20 μm, the off-state leakage current decreased to 3.2 pA/μm at VD = 0.1 V and VG = -10 V, which is more than two orders of magnitude lower than that in the conventional structure. In addition to a reduction in leakage current, other device parameters did not change significantly.

In this study, a 2 in. Ni field aided lateral crystallization (FALC) poly-Si thin-film transistor (TFT) (120×240)array was fabricated at the maximum process temperature of 500°Cusing an optimized current density distribution design. We investigated the correlation between crystallization and transistor characteristics in terms of transistor position in the array. Because an identical current density in the channel region of each pixel transistor was favorable to achieve uniform crystallization, an optimal common electrode design was chosen via Mathcad simulation. After the crystallization process, it was confirmed that the crystallinity variation in the transistor channels agreed well with the predicted simulation results. Furthermore, the positional variation in important transistor parameters in the array showed a good match with that of crystallization. The mean threshold voltage was 5.9 V (ΔVth=±0.2V)while the mean mobility was 92.5cm2V−1s−1with a variation of 9.8%. These values suggested that the uniform Ni-FALC poly-Si TFT arrays fabricated by the optimal design of the electrode were applicable to the active matrix organic light emitting display backplane.

It was demonstrated that an array of carbon nanotubes (CNT) can be grown using plasma-enhanced chemical vapor deposition on silicon oxide nanowires (SiOxNWs) to construct one-dimensional hierarchical heterostructure. In order to grow the CNTs on the SiOxNWs, the nanowire surface was decorated with Ni seed particles by direct physical deposition without any surface pretreatment. Nano-sized Ni seed particles allowed the CNTs to nucleate on the nanowire surface. Scanning and transmission electron microscopy verified the branches of CNTs projecting from the SiOxNWs. All CNTs were multi-walled and have an average diameter of 20 nm. These CNTs cover the entire length of the individual SiOxNWs. The CNT-coated SiOxNWs can be potentially used as a nanowire-supported catalyst with high active surface area.

In the blue phosphorescent organic light emitting devices (phOLEDs) with CBP:FIrpic, the relative intensity change of two peak, 465nm and 495nm were analyzed as degradation. As device is maintained on state, peak of 500nm is relatively increased than 465nm. It seems that these phenomena are induced by microcavity effect due to recombination region shift. As device is continuously driven, carrier blocking property of BCP is deteriorated and then recombination region is changed. Also the low triplet blocking property due to degradation of BCP let the EL spectrum to shift toward long wavelength and broaden.

The work function shift mechanism of the bilayer metal-gate electrode system has been investigated. An abrupt variation of the metal work function of Ru∕Ti∕SiO2was observed at a bottom layer thinner than 7nmwith the tunable range of nearly 1.3eV. Two plausible explanations are suggested for the work function shift. One is the deposition coverage ratio of two metal layers on gate dielectric due to the sporadic and fast islandlike growth of an ultrathin bottom layer roughly below 1nmand the other is the metal diffusion of the top layer for a thicker (<7nm)bottom layer.

As a low temperature crystallization process, the field-aided lateral crystallization (FALC) technique possesses outstanding advantages such as directional crystallization, high crystallization rate and inherent gettering effect owing to the effect of electric field and can lead on to high performance transistors. It turned out that the FALC behaviors resulted from the competition between electromigration effect and the magnitude of potential gradient. In order to demonstrate the feasibility of FALC process, an array of FALC processed poly-Si TFT was fabricated. The transistor characteristics were evaluated and compared to those fabricated without an electric field.

The effect of Cu and Au on field aided lateral crystallization (FALC) process of amorphous silicon films was investigated. Although both Cu and Au induced the crystallization of a-Si in contact with those metals, only Cu was able to induce the lateral crystallization toward a metal-free region. Especially, the crystallization caused by Cu atoms was noticeably accelerated at the edge near the negative electrode side in every pattern under the electric field, while the lateral crystallization was retarded at the positive electrode side. The crystallization velocity increased with the applied field intensity and the annealing temperature, but it decreased with the size of test pattern. However, electric field did not affect the crystallization by Au. The maximum crystallization velocity using Cu was 770 µm/h at 500°C in the electric field of 4 V/cm and the lateral crystallization was achieved at a temperature as low as 450°C.

The surface modification by plasma treatment is recently preferred to improve adhesion of metal on polymer. However, it may degrade the electrical or dielectric properties. To verify the drawbacks of surface modification, we compared biphenyldianhydride phenylenediamine (BPDA-PDA) polyimide after radio frequency (RF) Ar plasma treatments with as-baked polyimide. The confirmation of degrading the electrical properties of which surface is modified was attempted by means of equivalent circuit model of capacitor. Judging from that theory, we hypothesized that the electrical degradation can be easily checked out only by measuring resonance frequency. Capacitor before RF Ar plasma treatments showed the resonance frequency of 40.5 MHz (estimated). RF Ar plasma treatments for improving adhesion of metal on polyimide, however, lowered resonance frequency of polyimide to 34-35 MHz. From X-ray photoelectron spectroscopy (XPS) analysis, we certified that the degradation of electrical properties is derived out from the accumulated carbon atoms on the destroyed surface of polyimide layer. We deduced that although plasma treatments definitely did not affect the bulk dielectric constant of polyimide, it degraded the electrical properties of polyimide by lowering resonance frequency. Consequently, just measuring resonance frequency of capacitor can estimate the degradation of the electrical properties.

Perovskite manganite La-Ca-Mn-O (LCMO) thin films were deposited on LaAlO3(001) single crystal substrate by radio-frequency magnetron sputtering at room temperature. After annealing at 800-1000°C in O2atmosphere for 1 h, sheet resistance (R) of the LCMO thin films was measured by van der Pauw method in the range of 77-300 K. The characteristic resistance-temperature curves of all the annealed films showed typical insulator to metal transition behavior of colossal magnetoresistance (CMR) materials on cooling. The sheet resistance of LCMO films changes with temperature, conforming to a function of exp (?T) in the temperature range from 77 K to 230 K, which is applicable to an oxide thin film thermistor.

A new and simple cantilever type Pb(Zr, Ti)O3[PZT] microactuator was fabricated by adopting RuO2. The RuO2has reasonably good conductivity and stiffness and it can replace the double layer of electrode and supporting layer to a single layer in a cantilever beam. The RuO2, PZT and Al thin films were deposited on the Si substrate. The patterning of the Al was carried out by a lithography process and etched with a chemical wet etchant. The etching of PZT and RuO2were performed by a reactive ion etching system. The Si was etched isotropically to form a cantilever beam. The fabricated cantilever beam consists of Al, PZT and RuO2, and the thicknesses of the films are 0.40, 0.25 and 0.70 µm, respectively. The beams were from 140 µm to 275 µm in length and all of them were 60 µm wide. Driving tilt angles of the cantilever beams were almost proportional to the applied voltages.

We propose a noble crystallization method of amorphous silicon thin film in this study. Directional crystallization of amorphous silicon thin film was successfully achieved by applying a DC field during heat treatment. The crystallization temperature was lowered to 500°C by employing a trace amount of Ni. The lateral crystallization velocity was 21 µm/h when 53.5 V/cm electric field was applied at 500°C. It also showed the dependence on the applied field intensity. The directionality of the resulting crystallization depended on the polarity of the electric field. This noble technology can be applied to the fabrication of low temperature poly-Si thin film transistors on glass substrates.

Ferroelectric Pb(Zr, Ti)O3[PZT] thin films deposited on Pt-coated RuO2electrodes are found to have concurrent advantages in both fatigue and leakage current characteristics. Perovskite phase of PZT having a random orientation was obtained on as-deposited and Pt-coated RuO2bottom electrodes and the crystallinity increased slightly when the PZT films were deposited on Pt-coated RuO2. PZT films with hillock-free and fine-grained microstructures resulted in all the cases. The PZT films on hybrid electrodes (Pt/RuO2) showed a typical P-Ehysteresis loop. PZT films in all the cases did not exhibit fatigue until over 1010switchings regardless of the bottom electrodes. The asymmetric I-Vcurve of a PZT thin film on Pt/RuO2exhibited the Schottky behavior, which indicates that blocking contact is formed at the interface between PZT films and hybrid electrodes. The leakage current density of the PZT thin films on as-deposited and 30-nm-thick Pt-coated RuO2at 75 kV/cm was 4.73×10-6and 9.55×10-7A/cm2, respectively.