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Oxide-based thin-film transistors (TFTs) with a lateral in-plane electrode are self-assembled on paper substrates, and the electrical modulation effect of the in-plane electrode is investigated. A \SiO2-based solid-electrolyte film with high specific capacitance is used as the gate dielectric, and the operation voltage is reduced to less than 2.0 V. The threshold voltage (Vth) of such paper TFTs is tuned from -0.98 to 0.94 V by different voltage biases on the in-plane electrode. The threshold voltage shift (\Delta Vth) can be described by \Delta Vth = -(CG2/CG1)VG2, where CG2 and CG1 are the in-plane electrode and bottom-gate specific capacitance values. High electrical performance with a current on/off ratio of \6 \times \10^5 \sim \10^6, a subthreshold swing of 0.14 \sim 0.19 V/dec, and a mobility of \8.64 \sim \9.45\ \cm^2/\V\cdot \s is obtained at different in-plane electrode voltage biases. Such low-voltage paper TFTs are promising for low-cost and portable electronics. [ABSTRACT FROM PUBLISHER]

An electrophoretic display (EPD) cell with a triple-layered microcavity structure was fabricated using a convenient dry film resist. The inherent structural advantage arising from the function of the middle channel layer as a background colored state enabled the EPD to operate with two different-colored states by using a single type of electronic-ink particles, thereby eliminating the possible agglomeration of oppositely charged ink particles and supporting the potential application of the proposed structure to color the electronic paper. The preliminary operation of this new EPD structure was demonstrated as white and blue display states on a rigid glass exhibiting a contrast ratio of 1.5 : 1 with saturation voltages of +30 and -30 V, respectively. Successful demonstrations on both the indium–tin–oxide-patterned glass and flexible polyethylene substrates are also provided. [ABSTRACT FROM AUTHOR]

In this paper, reliability issues of In2O5Sn (indium-tin oxide: a transparent material) transparent gate recessed channel (TGRC)-MOSFET has been analyzed by considering the effect of interface trap charges (both positive and negative) present at the Si/SiO2 interface. Following device, characteristics are studied in terms of static, linearity, and intermodulation figure of merits. It is found that with the amalgamation of the transparent gate indium tin oxide on conventional recesses channel (CRC) MOSFET, it exhibits improved immunity against interface trap charges in comparison to CRC-MOSFET. In addition, the influence of ambient temperature (150-300 K) along with trap charges on TGRC-MOSFET has also been explored with an aim to analyze at which temperature of the device is more stable in the presence of interface defects (trap charges). Results obtained reveal that TGRC shows improved device performance at low temperature with trap charges being less influenced. Thus, this paper demonstrates that TGRC MOSFET can act as a promising candidate for low-power linear analog applications, where low temperature is required. [ABSTRACT FROM AUTHOR]

This paper investigates the issues of oxygen accumulation and variation in the high-resistance state of HfO2-based resistive random access memory (RRAM), with improvement attained by inserting a thin oxygen-vacancy-rich layer of indium-tin-oxide (ITO) film. By acting as the oxygen ion reservoir, this ITO thin film on the TiN electrode can further stabilize resistance switching (RS) characteristics. In terms of reliability, ac endurance, and retention tests confirm stable RS characteristics for the Pt/HfO2/ITO/TiN device. Finally, a conducting model was proposed to explain the influence of the ITO thin layer and clarify the physical mechanism of electrical improvements. [ABSTRACT FROM AUTHOR]

In this paper, several fundamental pseudo-CMOS digital circuits with n-type indium tin oxide-stabilized ZnO thin-film transistors (TFTs) were implemented and investigated. The optical transmittance of circuits varied from 77% to 92% throughout the visible wavelength band. Electrically, the operation frequency of inverters, nor gates, nand gates, D latches, and D flip flops were all found to exceed 10 kHz with a supply voltage of 10 V. Besides, 13-stage ring oscillators could be operated at 42 kHz with a propagation delay time of $0.92~\mu \text{s}$ when the supply voltage was set as 20 V. Among the state-of-the-art transparent designs, these proposed circuits based on the ITO-stabilized ZnO TFTs exhibited high-speed performance, which were promising as building blocks for transparent electronics with moderate frequency requirements. [ABSTRACT FROM AUTHOR]

In contrast to the conventional planar p-i-n photodiode and a metal-semiconductor-metal photodetector, the 3-D dual-gate photosensitive thin-film transistor (TFT) architectures presented here attain excellent photoresponse characteristics. Operating the device in the subthreshold regime further boosts the photoconductive gain as a result of light-induced decrease in the threshold voltage. This paper presents design considerations along with a performance comparison between 3-D photosensitive TFTs that have π- and FIN-shaped channels and conventional TFT with a planar channel. Our paper shows that the π-shaped structure tends to have a higher sensitivity while the FIN-shaped counterpart is more responsive with wider dynamic range. For both structures, a measured photoconductive gain of 104~106% is obtained with spectral responsivity ranging from near UV to near IR, and the photoresponse time in the range of tens of milliseconds. The 3-D dual-gate photosensitive TFT architecture appears to be very promising for large-area, low-level UV, visible, and IR detection applications. [ABSTRACT FROM AUTHOR]

In this paper, we report the fabrication of flexible and transparent InGaZnO thin-film transistors on muscovite mica substrates. The mica substrate is compatible with four-step photolithographic processes as well as high-temperature processes. The field-effect mobility, subthreshold swing, ON/OFF ratio, threshold voltage, and hysteresis voltage are improved after annealing both at 300° C and 400° C in nitrogen. The device demonstrates more stable performance under positive gate bias stress when annealed at 400° C than at 300° C. The electrical performances are stable when exposed to tensile bending cycles up to 10 000 times. The mica with devices shows small optical loss in the visible region, where the average transmittance is as high as 86.75%. [ABSTRACT FROM AUTHOR]

In this paper, a solar cell with amorphous silicon (a-Si) passivation that uses transition metal oxides (TMOs) for charge carrier collection has been modeled and analyzed for its performance. Charge carrier selection has been incorporated through selective band alignment provided by NiO and TiO2 TMOs for electrons and holes, respectively. The presence of a-Si interfacial layers for defect passivation prevents carrier loss due to high interface state densities at the Si/TMO interfaces. This structure is a potential candidate for high-efficiency solar cells (>25%) with a realistic approach towards the solution of high defect density. Optical analysis of the proposed structure has been done to analyze the amount of light entering the silicon and capable of generating electron–hole pairs. The amount of light lost has also been quantified into reflection loss, parasitic absorption, and back metal absorption. Impact of surface passivation quality and doping of NiO and TiO2 on its performance has been analyzed through the detailed device simulations. This provides a realistic pathway for engineering of passivation quality and doping of metal oxides for improved performance. [ABSTRACT FROM PUBLISHER]

In this paper, hybrid transparent conductive electrodes (TCEs) consisting of oblique-angle deposited indium tin oxide (OAD ITO) and silver nanowires (Ag NWs) were developed forGaN-based light-emitting diodes (LEDs). The 100-nm thick OAD ITO acted as an Ohmic contact to p-GaN with negligible light absorption having optical transmittance as high as approximately 99% at 450 nm, and Ag NWs acted as a favorable current spreader with sheet resistance as low as $19.9~\Omega $ /sq. Consequently, the hybrid TCEs consisting of OAD ITO and Ag NWs yielded an optical transmittance of 93% at 450 nm, a sheet resistance of 18.9 \Omega $ /sq, and a specific contact resistance of {2.1} \times {10}^{-2} \Omega \cdot cm2. LEDs fabricated with hybrid TCEs demonstrated improved electrical properties and greater optical output powers than the reference LEDs. This was due to the combined effects of the improved optical transparency, the enhanced current spreading, and the surface roughening effect. [ABSTRACT FROM PUBLISHER]

For the photovoltaic effect (PE), the surface potential is suggested to be an adverse factor, and researchers usually try to increase the thickness of the conductive layer or the number of strip electrodes to avoid it. However, the potential can still not be eliminated. More importantly, the huge cost has to be paid, and the photovoltaic performances are largely reduced. While the drawback of potential in PE may become excellent merit in lateral PE (LPE) due to their different working mechanisms. Moreover, the decreasing thickness of the conductive layer may be inversely used as an efficient method to modulate the LPE performances. In this paper, the indium tin oxide (ITO) conductive layer thickness-dependent LPE responses are well studied in the copper indium gallium selenide (CIGS) heterostructure. The LPE response is significantly improved with ITO thickness decreasing from 150 to 10 nm, and the thickness-dependent enhancement is strongly dependent on the illumination intensity, especially in high illumination intensities, a nonmonotonic thickness dependence is obtained. In addition, it is found that the heterostructure exhibits an ultrafast response speed of ~14.5 $\mu$ s/~15.0 $\mu$ s, and what is more, the response time nearly remains constant without depending on the ITO thickness. [ABSTRACT FROM AUTHOR]

In this paper, ZnO nanorod humidity sensors with dye-sensitized solar cells (DSCs) were prepared on indium tin oxide conductive glass. The average diameter and length of the ZnO nanorods were ~100 nm and $\sim 1.5~\mu \text{m}$ , respectively. After ZnO nanorods were grown, TiO2 film was coated by TiO2 with a nanoparticle size of approximately 26 nm through the doctor blade method. The sensitizer N3 was used for charge transfer on the DSCs. The solar photovoltaic conversion efficiency of the DSCs was approximately 4.7%. Humidity sensors were used for measurement under ultraviolet (UV) light at 365 nm. During UV illumination, the current increased under low humidity and gradually decreased under high humidity. The integrated device exhibited similar stable and sensitive performance as the traditional ZnO humidity sensor. Experimental results revealed that DSCs could be integrated with ZnO nanorod humidity sensors to create a self-powered integrated device that has potential Internet of Things applications. [ABSTRACT FROM AUTHOR]

In this paper, fully solution-processed organic solar cells were fabricated on prepurchased tin-doped indium oxide (ITO)-coated glass using the inverted architecture. Solution-processed electrodes consisting of ITO nanoparticle, silver (Ag) nanowire, or Ag nanoparticle films were used as the anode in the devices. Electrode deposition for solution-processed components was accomplished by using a commercially available airbrush with compressed dry nitrogen as the carrier gas. Morphologies of the deposited electrodes and the solution-processed electron blocking layer can be seen as topography images using atomic force microscopy. Cells fabricated with a solution-processed electrode show comparable device performances to that of an evaporated electrode using a similar structure. [ABSTRACT FROM AUTHOR]

In this paper, the power- and wavelength-dependent lateral photovoltaic effect (LPE) in an indium tin oxide/Si structure is first studied at different temperatures ranging from 292 to 80 K. It was found that the position sensitivity increased gradually until it became saturated with increasing laser power at a constant temperature, and the saturated position sensitivity increased nearly linearly from 2.47 to 3.91 mV/mm with increasing wavelength from 405 to 980 nm at 292 K. More importantly, the position sensitivity also increased considerably with decreasing temperature from 292 to 80 K, and the position sensitivity of 7.47 mV/mm at 80 K is about 1.91 times as large as that of 292 K under illumination of 70 mW for 980-nm laser. Based on the temperature-dependent Schottky barrier height, these results can be well explained. The significant observation of the improved LPE in infrared region makes this structure great potential in infrared position sensitive detectors, especially at low temperature. [ABSTRACT FROM AUTHOR]

This paper investigates material modifications induced by cosputtering indium-tin oxide (ITO) with gadolinium (Gd) at two different power levels. In addition, resistance switching (RS) properties were also verified for use as an insulator in resistive random access memory (RRAM). Comparison of scanning electron microscope (SEM) measurements for the two different cosputtering powers indicated significant changes of the ITO surface. Transparency was also verified by an N&K analyzer measurement, with results indicating a constant in transparency induced by the lower power Gd doping, indicating potential for transparent applications. Furthermore, the mole fraction ratio defined by X-ray photoelectron spectroscopy reveals a Gd2O3 peak, a likely reason for the ITO thin film becoming less conductive. This ITO/Gd:ITO/TiN RRAM can exhibit stable and robust RS characteristics at a lower forming voltage. In addition, lower operating voltages, including both SET and RESET voltages, can be obtained. Reliability tests including endurance and retention were carried out to confirm its RS stability. The RS mechanism of this ITO/Gd:ITO/TiN device was also investigated with the current–voltage (${I}$ – ${V}$) fitting method. Moreover, temperature effects were also applied to verify the high-resistance state (HRS) mechanism. Finally, a conduction model was proposed to clarify the RS characteristics and confirm that the ITO/Gd:ITO/TiN device is appropriate for data storage. [ABSTRACT FROM AUTHOR]

In this paper, the optical and electrical pulse responses of an optimized high-speed organic light-emitting diode (OLED) is investigated as a function of the pulse duration. The original design is based on the coplanar waveguide electrodes that are implemented on a transparent and conductive oxide thin film. The designed electrodes with reduced serial resistances (13 $\Omega $) allow to maximize the pulse energy delivery and to feed the organic device with short electrical pulses of few nanoseconds for the first time. This is achieved by designing the electrodes to have 50- $\Omega $ characteristic impedance, thanks to microwave techniques, and by implementing small values of capacitance (4.5 pF). The experimental results demonstrate $\boldsymbol \mu $ -OLED electrical and optical responses to electrical excitation pulses as short as 2.5 ns, for the first time, and state-of-the-art current densities above 1.7 kA/cm2. Moreover, and rather unexpectedly, the developed characterization procedure to extract the reported results demonstrated the first direct measurement of the electroluminescence lifetime of organic materials in the nanosecond time scale. [ABSTRACT FROM AUTHOR]

We suggest functional passivation layers in the form of a distributed Bragg reflector (DBR) composed of ZnS and LiF for transparent thin-film transistors (TFTs) to improve the stability under negative bias illumination stress (NBIS). The luminous transmittance of the DBR was 82.0% when the number of dyads was 3.5, and the thicknesses of ZnS and LiF were 42 and 85 nm, respectively. We applied the DBR to TFTs based on amorphous indium-gallium-zinc oxide without the degradation of electrical performance, such as the mobility, ON–OFF ratio, subthreshold swing, and $V_{{\mathrm{\scriptscriptstyle ON}}}$ . The luminous transmittance of the TFT with the DBR was measured as 71.6%. $\Delta V_{{\mathrm{\scriptscriptstyle ON}}}$ of the TFT with the DBR was reduced to −1.119 V compared with that of the reference TFT, which is −3.261 V when a 1.25 MV/cm electric field was applied, and white light was illuminated during 3000 s. This confirms that the functional passivation layers suggested, in this paper, provide a solution to suppress the instability of TFTs in the NBIS and enhance the optical transmittance of transparent displays. [ABSTRACT FROM PUBLISHER]

The development of a facile, low-temperature, and low-cost method to fabricate highly sensitive and optically transparent resistive pressure sensors remains a challenge. In this paper, a graphene/polyaniline-embedded polyvinyl butyral (GPANI-PVB) composite film is employed as the active layer in a resistive pressure sensor; this film is ultrathin, highly sensitive, optically transparent, anisotropically conductive, highly durable, highly flexible, and bending insensitive. A flexible touch panel based on the GPANI-PVB composite film is fabricated using a facile process, which supports multitouch and multilevel pressure detection. The GPANI-PVB composite film offers great potential for applications in flexible and transparent interactive electronic devices. [ABSTRACT FROM AUTHOR]

A highly transparent resistive random access memory with a configuration of multilayer graphene (MLG)/ Dy2O3 /indium tin oxide (ITO) structure is demonstrated in this paper. The fabricated device is transparent, with 80% transmittance at 550 nm. The MLG/ Dy2O3 /ITO device shows unipolar resistance switching with a low operation current (<100~\muA) , low operation voltage (<1~V) , low power consumption (<100~\muW) , high resistance ratio (>10^4) , fast switching speed (<60~ns) , reliable data retention, and promising cycle endurance properties (>200~cycles) , which makes a step toward the realization of low-power transparent electronics for next-generation nonvolatile memory application. The MLG/ Dy2O3 /ITO device exhibited typical filamentary-conduction-type resistive random access memory behavior and no forming process is required. High resistance state (HRS) increases with a reduced device area while low resistance state (LRS) is insensitive to the device sizes. Moreover, Raman spectra obtained in pristine state, HRS, and LRS indicate that the lower power consumption of MLG/ Dy2O3 /ITO device is attributable to the formation of oxygen graphene layers. [ABSTRACT FROM AUTHOR]

In this paper, the properties of hybrid-phase microstructural indium tin oxide-stabilized ZnO thin films and the relevant high-performance thin-film transistors (TFTs) were systematically investigated. The optically extracted Urbach energy revealed that such thin films owned less band-tail state trapping in comparison with that of the corresponding amorphous thin films. This was determined by better atomic arrangement and might realize higher drift mobility theoretically. The influence of deposition parameters such as oxygen partial pressure ratio (PO2) and direct-current power ( \textP\mathrm{ DC}) on thin films was discussed in detail. Then, the TFTs with optimal co-sputtering conditions were fabricated. Such devices exhibited a typical field-effect mobility of 26.1 cm2/ \textV\cdot \texts , threshold voltage of 0.5 V, on–off ratio of over 10^9 , and extremely low subthreshold swing of 89 mV/decade. Meanwhile, the spatial uniformity, air stability, and repeated switching behavior of devices were demonstrated to be excellent. [ABSTRACT FROM PUBLISHER]

This paper investigates the characteristics of applying indium–tin oxide (ITO) with and without nitride gas (N2) as the insulator in resistive random access memory (RRAM). After cosputtering an ITO target with N2 as the insulator and capping the same ITO material as the top electrode, the device exhibits rectifier and resistance switching characteristics before and after the forming process, respectively. The Schottky diodelike rectifier mechanism was also verified by various temperature measurements. Furthermore, robust resistance switching at a positive forming voltage, smaller than that required during negative bias forming, can be achieved. Both positive and negative forming processes are examined with current fitting results, which show different dominant mechanisms when using positive or negative biases. All these mechanisms have also been verified by temperature effect experiments, which confirmed the dominant conduction mechanisms. This, in combination with the fact that the positive forming voltage itself is smaller than the negative forming voltage, and decreases with device scale down, provides two highly beneficial results. This good performance achieved by using ITO with N2 suggests significant progress of RRAM and remarkable potential applications. [ABSTRACT FROM PUBLISHER]

This paper proposes low power consumption resistance random access memory (RRAM) devices with indium–tin-oxide (ITO) electrodes. The development of the Internet of Things (IoT) is a trend in future technology, but the bottleneck in IoT development is high power consumption; therefore, targeting low-power-consumption memory is crucial for the IoT. ITO-capped RRAM devices have been shown to exhibit outstanding performance and low power consumption, and here, we propose an oxygen accumulation mechanism by analyzing device characteristics. We find that the conduction current mechanism will be affected by oxygen absorbance in the ITO electrode. During the forming and set processes, oxygen ions will be propelled into the ITO electrode due to its oxygen vacancy-rich property; therefore, we find Schottky emission both at high-resistance state and low-resistance state and that the device exhibits an automatic current compliance property. Varied stop-voltage measurements were carried out to verify the device mechanism. Because of its capability for oxygen storage, the thick ITO layer was confirmed to affect the characteristic due to a difference in oxygen gradient. A new structure and novel material are proposed, based on the devices with ITO electrodes to improve performance and reduce power consumption. [ABSTRACT FROM PUBLISHER]

In this paper, indium-tin-oxide (ITO) was used to act as both insulator and top electrode in resistive random access memory (RRAM) on identical bottom substrates. This is achieved by cosputtering an ITO target with nitride (N2) or oxygen (O2) gas as the insulator; then capping by an ITO electrode, such that both the rectifier and RRAM characteristics can be achieved before and after a forming process, respectively. In contrast, using pure ITO as an insulator does not exhibit RRAM behavior. To verify the rectifier and RRAM characteristics, material analyses and electrical measurements at various temperatures were conducted. Reliability tests including retention and endurance were also applied to verify the resistance switching stability. Finally, the rectifier and RRAM conduction models were proposed to examine the resistance switching behaviors. By applying the ITO material as both electrode and insulator, the resistance switching characteristic with high reliability is thus obtained. [ABSTRACT FROM AUTHOR]

This paper proposes a new design module for reverse-connected microelectrochemical machining ( \mu-ECM), which is based on a novel electrochemical reaction that offers the fast removal of indium-tin-oxide (ITO) nanostructures from the surfaces of color filters in displays. Unlike general \mu-ECM models, the reverse-connected \mu-ECM model is implemented by connecting a workpiece to the cathode and an electrode to the anode of a dc power supply. During the course of machining, electrons travel from the cathode to the anode, so that the ITO film is lifted and removed at high speed by an electric field. In general \mu-ECM models, a workpiece is connected to the anode, an electrode is connected to the cathode, and the material removal is achieved by dissolution. In contrast, the reverse-connected \mu-ECM model provides higher removal efficiency and higher surface quality of color filters in displays during machining processes, thereby breaking new ground in superfine machining for applications in the photoelectric semiconductor industry. [ABSTRACT FROM AUTHOR]

Inverted polymer solar cells (iPSCs) have shown a great potential in organic photovoltaics due to its enhanced stability and large-scale roll-to-roll processing. Metallated conjugated polymers also show promise as a donor material in the PSCs. In this paper, the role of solvents on the performance of inverted structure metallated PSCs was understood. Chlorobenzene (CB) and toluene were used as solvents to obtain the optimum morphology for improved device efficiency. To understand the charge transport properties and charge carrier lifetime in metallated polymer iPSCs, atomic force microscopy and transient photocurrent measurements were performed. The results showed that the CB as a solvent can improve the morphology of the active layer and enhance the performance of metallated iPSCs. [ABSTRACT FROM AUTHOR]

We demonstrate the ink-jet printed fabrication technique for TiO2-based memristor, followed by detailed analysis of electrical characteristics and development of a new model that considers observed phenomena of quantized conductance steps. The existence of pinched hysteretic current–voltage characteristics is evidence of memristive behavior, provided by the reversible atomic rearrangement taking place in the functional layer. For the first time, performed electrical measurement on the micrometer thickness devices based on TiO2 active layer has captured the plateaux steps of the conductance at integer multiples of elementary quantum conductance. This behavior is consistent with the assumption that transport from electrode to electrode emerges through confined paths of conductive filaments with radius in the nanometer size range. Moreover, we introduce a novel model, based on the diffusion equation for ballistic transport in memristive devices, which considers the conductance plateaux steps. [ABSTRACT FROM AUTHOR]

We report a bidirectional, treated graphene oxide electrode-based organic bulk heterojunction solar cell. The nature of interfaces in the photoactive region (between PTB7/PC71BM), charge transport, and the role of treated graphene’s transparency in the device performance are investigated. Use of treated graphene reduces the sheet resistance (200–75 $\Omega$ /sq) of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate thin film and improves the organic solar cell performance over a wide spectral range (250–750 nm). Due to: 1) the charge neutrality between PTB7 and PC71BM and 2) lowering of defect states in the electron collection layer, the overall solar cell power conversion efficiency ($\eta$) reaches 8.4% ± 0.23%; a fill factor of 69.5%, short-circuit current density of ${\sim} {16.1}\,\,\text {mA}\cdot \text {cm}^{-{2}}$ , and internal quantum efficiency of ~68.8%. [ABSTRACT FROM AUTHOR]

This paper presents ultrathin and highly sensitive input/output devices consisting of a capacitive touch sensor (Cap-TSP) integrated on thin-film-encapsulated active-matrix organic light-emitting diodes (OLEDs). The optimal structure of the electrically noise-free capacitive touch sensor, which is assembled on a thin-film-encapsulated active-matrix OLED (AMOLED) display, is obtained by investigating the internal electrical field distribution and capacitance change based on the Q3D Extractor model. Electrostatic simulations have verified malfunction-free electrical signals for 4-in diagonal-sized capacitive touch sensors on AMOLEDs possessing a 100- \mu\m-thick optically clear adhesive (OCA, \varepsilonr = \1.4) layer. The prototype OLED platform using the capacitive touch sensors exhibits an overall thickness of 1.2 mm, which is the lowest thickness for commercially available OLED platforms. [ABSTRACT FROM AUTHOR]

The electric and optical impulse response of two types of high-speed OLED (HSOLED) driven by ultrashort electrical pulses is investigated. The two HSOLED were designed and manufactured to be characterized in the presence of electrical pulses ranging from 10 to 100 ns in duration and a repetition rate of 10 Hz. The impact of the OLED geometry and the fabrication process on the time response is investigated. This is the first time that an optimized HSOLED exhibits an electrical time response as low as 2.1±0.6 ns and also shorter than the device optical decay time (9.8± 0.2 ns). Moreover, the HSOLED measured current density reaches 3.0 kA/cm2, the highest value reported in the literature, with state-of-the-art electroluminescence of 12 W/cm2. [ABSTRACT FROM PUBLISHER]

For most large-area applications, spatial nonuniformity of transistor characteristics makes it difficult if not impossible, to achieve adequate performance. Nonuniform parameters may lead to variations in color or gray level, which is commercially not viable. A variation in threshold voltage, mobility or ${I}-{V}$ characteristics of an organic thin-film transistor (OTFT) in a pixel circuit can result in unacceptable variation in the current driving the organic light-emitting diode (OLED) which accounts for large nonuniformities in the pixel brightness. Given its importance, a fast and straightforward method for characterization of device variations would be of great help in the process development and optimization. In the present work, a simple, easy to fabricate two-terminal asymmetric metal–insulator–semiconductor (AMIS) capacitive test structure is proposed for quick and accurate characterization of the process-induced nonuniformities in mobility, threshold voltage, and drain current. The capacitance–voltage (${C}-{V}$) characteristic of the proposed AMIS structure is derived mostly from the channel, and its contribution to the total capacitance at any given frequency depends on channel properties including mobility and threshold voltage. At low frequencies, the ${C}-{V}$ characteristics become independent of the series resistances, and hence, complex techniques can be sidestepped for accurate estimation of channel properties. The simulation results are presented to demonstrate the concept using a single AMIS test structure. The experimental results obtained with top contact pentacene based on AMIS arrays are presented to show the concept and advantages of the proposed structure. [ABSTRACT FROM AUTHOR]

The rational design and fabrication of zinc oxide (ZnO) nanowire (NW) lateral field electron emission device and the possible application as a display pixel structure are reported. In the device, the cathode and anode are ranked side-by-side on the same panel. The NW-clusters were controlled to locally grow on the edges of the electrodes with different tilted status, i.e., in angle range of 75^\circ–110^\circ, 0^\circ–110^\circ, and 0^\circ–57^\circ, respectively. The devices with NWs at different tilt-angle showed distinct field electron emission properties. The device with 0^\circ–57^\circ tilted NWs possess the best performance, i.e., an emission current of 9.3 \muA (current density: 6.22 A/cm^2) was obtained at a low cathode-anode (50 \mum in separation) bias of 477 V. Stable cathodoluminescence was observed from the indium titanic oxide anode, suggests a possibility for display application. Mechanisms responsible for the enhanced field electron emission and the related device physics are proposed. Significantly, the low temperature (\sim80^\circC) solution-phase growth of ZnO NWs enables the fabrication of the devices on flexible polyimide substrate, which has also been demonstrated here. This paper opens up possibilities on developing NW-based lateral field electron emission device for vacuum micro/nanoelectronics applications. [ABSTRACT FROM AUTHOR]

The high-performance ZnO thin-film transistors (TFTs) were fabricated on indium tin oxide glass with high-capacitance atomic layer deposition (ALD)-processed ZrO2 as the gate dielectric. The 5-nm ultrathin ZrO2 film showed a very high areal capacitance of 820 nF/cm2 at 20 Hz, a relatively high breakdown field of 14 MV/cm, and low surface root-mean-square (rms) roughness of 0.22 nm, making it possible for ZnO/ZrO2 TFT to not only be operated by an ultralow operating voltage of 1 V but also present a near theoretical limit subthreshold swing of 69 mV/dec. Furthermore, the ZnO TFT with a 5-nm ZrO2 gate dielectric exhibited excellent performance, such as a high Ion/Ioff of 107, large field effect mobility of 36.8 cm2/Vs, low-density of trapping states (${N}_{{\text {trap}}}$) of $1.6\times 10^{{11}}$ eV−1cm−2, and negligible hysteresis. In addition, the electron transport mode was built to explain the high mobility of nanocrystalline ZnO TFT. As a result, the ultralow operating voltage TFTs exhibited great potential for low-powered electronics applications. [ABSTRACT FROM AUTHOR]

We studied the effects of postannealing on the performance of polyfluorene organic light-emitting diodes (OLEDs) with a pure poly(9, $9'$ -dioctylfluorene-co-benzothiadiazole) (F8BT) emissive layer. After annealing at 150 °C–200 °C, the OLED exhibited the lowest voltage and highest luminance. This correlated well with the highest crystallinity of the F8BT film, as revealed by X-ray diffraction. As the temperature was raised up to 300 °C, the voltage at 50 mA/cm2 increased by 2.7 V, and the luminance decreased by 44%, whereas the device lifetime was markedly extended by as much as 13 times. The loss of crystallinity at high temperatures suggested that structural disorders were created, resulting in degraded charge transport and radiative process. Our study demonstrates the necessity of posttreatment above the glass transition temperature to obtain desirable efficiency and lifetime of solution-processed polyfluorene OLEDs. [ABSTRACT FROM AUTHOR]

Amorphous oxide-based thin-film logic circuits have been fabricated using only an n-type amorphous silicon–zinc–tin–oxide (a-SZTO) channel layer with different source/drain electrodes. Enhancement-mode thin-film transistors (TFTs) were fabricated with oxide electrodes. Depletion-mode TFTs were fabricated with metal electrode. Work functions were measured by Kelvin probemicroscopy. The barrier heights ($\Phi _{\textsf {B}}$) between the a-SZTO channel layer and the electrode were measured to be 1.831, 2.341, and 2.339 eV for the Ti/Al electrode, Indium–silicon–oxide (ISO) electrode, and indium–tin–oxide (ITO) electrode, respectively. The physicalmechanism on the variation of sheet and contact resistances was investigated using a transmission line method, and the change in the resistances is closely related to $\Phi _{\textsf {B}}$. Inverters were fabricated, with different $V_{\textsf {TH}}$ values adopted simply by using different contact characteristics between various electrodes and the semiconductor channel. High values of voltage gains in inverters were obtained: 12.33 (ISO) and 11.75 (ITO) at $V_{\textsf {DD}}= 5$ V. Itwas also confirmed that more complicated n-type-based NAND and NOR thin-film circuits, implementedwith different electrodes, functioned as conventional logic circuits. This simple fabrication method of thin-film logic circuits opens the possibility of implementing next-generation stacked integrated circuit technology. [ABSTRACT FROM AUTHOR]

2-D transition metal di-chalcogenides are the promising candidates for ultralow intensity photodetection. However, the performance of these photodetectors is usually limited by ambience induced rapid performance degradation and long-lived charge trapping induced slow response with a large persistent photocurrent when the light source is switched off. Here, we demonstrate an indium tin oxide (ITO)/WSe2/SnSe2-based vertical double heterojunction photoconductive device where the photo-excited hole is confined in the double barrier quantum well, whereas the photo-excited electron can be transferred to either the ITO or the SnSe2 layer in a controlled manner. The intrinsically short transit time of the photoelectrons in the vertical double heterojunction helps us to achieve high responsivity in excess of 1100 A/W and fast transient response time on the order of ${10}~\mu \text{s}$. A large built-in field in the WSe2 sandwich layer results in photodetection at zero external bias allowing a self-powered operation mode. The encapsulation from the top and bottom protects the photo-active WSe2 layer from ambience induced detrimental effects and substrate induced trapping effects helping us to achieve repeatable characteristics over many cycles. [ABSTRACT FROM AUTHOR]

A novel-gated structure of aluminum (Al)—perovskite (CH3NH3PbI3)—indium tin oxide (ITO), with Al as source and ITO as drain terminals, has been reported. Ambipolar nature of CH3NH3PbI3 has been explored for the device channel. Two Schottky junctions are present at source–channel and channel–drain junctions with barriers of 0.4 and 0.6 eV, respectively. Both, n- and p-type FET-like characteristics have been observed, when the device was biased, accordingly. The triangular tunneling has been observed in the output and transfer characteristics. The device shows a higher current on-off ratio ( ${I}_{ \mathrm{\scriptscriptstyle ON}}/_{ \mathrm{\scriptscriptstyle OFF}})$ of 106 with a steeper and improved sub-threshold swing (SS) of 20 ± 2 mV/decade for P tunnel field-effect transistor (TFET). However, for N TFET, ${I}_{ \mathrm{\scriptscriptstyle ON}}/_{ \mathrm{\scriptscriptstyle OFF}}$ of 104 with SS of 30 ± 2 mV/decade has been obtained. [ABSTRACT FROM AUTHOR]

We proposed an eight-domain vertical alignment (VA) liquid crystal (LC) mode, operated by dual pixel domains of fishbone-structured electrodes for dual threshold (F-DT) voltages in the VA mode, which can improve off-axis gamma distortions without additional electronic circuits and fabrication procedures compared with the conventional multidomain VA modes. In the proposed F-DT VA mode, different threshold voltage levels can be obtained for the main- and subpixel regions by utilizing different field-induced LC reorientations determined by the pixel electrode structures, whose properties are especially enhanced in low-voltage regimes. When the relative area ratio ( R A={A}\text {main}/{A}\text {sub} ) between the main- and subpixel domains was R A=\text {5} , these dual threshold properties of the F-DT VA mode improved the off-axis gamma distortion index (GDI) value up to 34.04% at the oblique viewing condition of \theta = 60^\circ , compared to the conventional patterned VA (PVA) modes, while maintaining the maximum transmittance level. The proposed pixel electrode design scheme could be applied to further improve the GDI value simply by controlling RA , where the GDI of the F-DT VA mode was improved by 39.17% and 17.05% at R A= {2} , compared to the conventional PVA and micropatterned VA modes, respectively. [ABSTRACT FROM PUBLISHER]

Single-active layer (SAL) and dual-active layer (DAL) oxide thin-film transistors (TFTs) are fabricated using the same process conditions and compared side by side. The SAL channel consists of amorphous In–Ga–Zn–O (a-IGZO), and the DAL of ultrathin In–Sn–O and a-IGZO. The DAL TFT exhibits strongly improved performance compared to the SAL TFT such as higher mobility of 31 cm ^\textsf 2\cdot \textV^-\textsf 1\cdot \texts^-\textsf 1 , smaller subthreshold swing of 175 mV/dec, and better positive bias temperature stress stability. Technology computer-aided design simulation is used to investigate the SAL and DAL device performance. A mapping technique is used to directly correlate the transfer characteristics to the subbandgap density of states. The simulation suggests that the improved performance of the DAL TFT is due to an improved gate insulator/channel interface with an approximately one order of magnitude lower interface trap density. [ABSTRACT FROM PUBLISHER]

For the first time, we are proposing characteristic equation, which describes the behavior of an organic permeable base transistor (OPBT). For this, an OPBT has been fabricated and studied through the experimentally obtained IC / gm versus V\mathsf {BE} (base-emitter voltage) characteristics. The characteristic equation, i.e., collector current, IC = {k} ( V\mathsf {BE} - V\mathsf {th})^{n} has been obtained through curve fitting and mathematical formulations. Six OPBTs (modified by inserting a layer of barrier material of either N, \textN^\prime [(-di-[( \alpha -naphthyl)-N, 1^{\prime } -biphenyl)-4, 4^{\prime } -diamine ( \alpha -NPD) or N, \textN^\prime -Bis(naphthalen-1-yl)-N, \textN^\prime -bis(phenyl)-2,7-diamino-9, 9-(Spiro-NPB) between emitter and base layers) confirm that their transfer characteristics follow this equation with n varying between 1.1 and 2.2. The n has been found to be dependent on barrier material. The gain of the device is {A}_{O} = \textit {nV}_{E} / V\mathsf {BE} , {V}_{E}$ being the early voltage. [ABSTRACT FROM PUBLISHER]

Wavelength-selective absorption phenomena of silicon-based vertical nanowire (NW) photodetectors (PDs) are investigated using 3-D numerical simulations. The difference in the refractive indexes between silicon NW and its surrounding material induces diameter-dependent waveguide effects at several specificwavelengths for asymmetric as well as symmetric structures. But the asymmetric NW PDs with a large difference in diameter between the top side and the bottom side have loss of waveguide effects. All the NWPDs achieve high external quantum efficiency (EQE) peaks with an increase in NW height. Decreasing the NW pitch or increasing the NW density also increases the EQE peak values for awide range ofwavelengths, but too densely packed NWs induce high coupling between the nearest NWs, thus losing wavelength-selective properties. Vertical NW PDs having slightly bottom-wide asymmetric structure decrease reflectance and transmittance of the incident light because of the narrow top-side and wide bottom-side silicon NW cross sections, respectively, thus achieving higher EQEs. Bottom-wide asymmetric NW PDs are promising to enhance the optical characteristics as well as to maintain waveguide properties for optical sensor applications. [ABSTRACT FROM AUTHOR]

Highly transparent and low-resistive multilayered gate electrodes, MoO3/indium–tin oxide (ITO)/Ag/ZnS (MIAZ) playing as the high-work-function layer, the nonreactive interface layer, the lateral conduction layer, and the index-matching layer, respectively, have been investigated for the application to the transparent oxide thin-film transistors (TFTs). The transmittance of the optimized MIAZ electrode is 92.46% and the sheet resistance is 7.77~\Omega / \Box . The top gate InGaZnO TFT with this gate electrode shows the mobility of 11.57 cm2/( \text {V}\cdot ~\text {s} ) and positive V_{\text {th}}$ of 0.210 V compared with that with single ITO gate electrode of which V_{\text {th}} is −0.086 V. [ABSTRACT FROM AUTHOR]

Lead-based organic–inorganic hybrid perovskite single crystals (OIHP SCs) offer promising opportunity for X-ray detection and imaging owing to their high X-ray attenuation coefficient, excellent optoelectronic properties, and simple fabrication processes. Nevertheless, it remains a key challenge to reduce its dark current and meanwhile maintain a high sensitivity. Herein, we developed an on-substrate method for growing methylamine lead bromide (MAPbBr3) SCs on aluminum oxide (Al2O3) layer coated indium tin oxide (ITO) glass. The photodiode based on this approach exhibits an ultralow-dark-current density of 1 nA cm−2 at an operative voltage of −5 V, a signal-to-noise ratio (SNR) more than 80 dB, and meanwhile retaining a high X-ray sensitivity of 2.02 $\times 10^{{3}}\,\, \mu \text{C}\cdot $ ${\mathrm {Gy}}_{\text {air}}^{-1} \cdot $ cm−2. Our further investigation reveals that the dark current was reduced due to two beneficial effects of the Al2O3 layer in tandem, including the interfacial defect passivation and blocking of hole injection by increased interfacial energy barrier. Our approach sheds light on advancing the fabrication of high-performance OIHP SCs-based X-ray sensors that can be potentially integrated with large-area readout panel at low temperature. [ABSTRACT FROM AUTHOR]

We propose the optimal p-bonding electrode (p-BE) schemes on single-crystalline Ga-doped ZnO (ZnO:Ga) in GaN-based light-emitting diodes (LEDs) by means of Cr (3 nm)/Al0.9Cu0.1 (50 nm) reflection-assisted layer (RAL) and Pd0.8Al0.2/Ni/Au layers. Design factors for the p-BE were described from standpoints of bond strength, electrically equivalent circuit, and photon reflection. From contact test results, the Cr/Al–Cu RAL/Pd–Al/Ni/Au scheme is much more attractive than other schemes, indicating the optimal scheme for ZnO transparent-conducting electrode (TCE). The comparisons from device-performance characteristics showed that the forward voltage and output power of the LED having Cr/Al–Cu/Pd–Al/Ni/Au in the open-structured ZnO:Ga are significantly improved, as compared to those of LEDs with conventionally used Cr/Al/Ni/Au in the open-structured indium tin oxide and ZnO:Ga. In addition, for acceleration test under high-stress current density of 99 A/cm2, a degradation rate of the proposed bonding electrode-applied LED is $\sim 190$ times as low as that of the other LEDs, indicating longer lifetime and much more thermal stability. Based on the test results, the suggested p-BE is quite attractive for achieving high-performance and excellent reliability GaN-based LEDs with a single-crystalline ZnO TCE. [ABSTRACT FROM AUTHOR]

We demonstrated the methylammonium lead iodide (CH3NH3PbI3) perovskite-based solar cells (SCs) with nickel (Ni)-oxidized nickel oxide (NiOx) hole transport layer. The CH3NH3PbI3 perovskite-based SCs with Ni-oxidized NiOx have better short-circuit current density ( JSC) , open circuit voltage ( VOC) , and conversion efficiency ( $\eta $ %) than poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS). In addition, the transmittance and work function increased with increasing oxidation temperature of Ni-oxidized NiOx layer. The larger transmittance and work function of Ni-oxidized NiOx could result in less light absorption and hole transport energy loss, respectively. Furthermore, Ni-oxidized NiOx at 450 °C shows the smoothest surface morphology, which could result in the spin-coated CH3NH3PbI3 perovskite film to have better crystal quality. Therefore, the SCs with 450 °C Ni-oxidized NiOx hole transport show the largest $\eta $ % of 7.75% that is $\sim 1.78$ times larger than that of SCs with PEDOT:PSS hole transport layer. [ABSTRACT FROM AUTHOR]

It was demonstrated that low-operating-voltage bottom-gate top-contact (BGTC) structure thin-film transistors (TFTs) were fabricated using solution-processed amorphous zinc indium tin oxide (ZITO) and hafnium aluminum oxide (HAO) films. Due to the excellent chemical stability of ZITO film and high etching selectivity between ZITO and indium tin oxide (or between ZITO and Mo), the manufacture of BGTC structure requires only traditional lithography and wet etching. The usage of high- k HAO films lowered the operating voltage (below 2 V) of the TFT devices. TFT devices based on ZITO and HAO films annealing at 500 °C showed a saturated field-effect mobility of 13.5 cm ^{\mathrm {\mathbf {2}}} V ^{\mathrm {\mathbf {-1}}} s ^\mathrm \mathbf -1 , a ^^^^ small subthreshold swing of 87 mV/decade, a large ON-to-OFF current ratio of 7.2\times 10^\mathrm \mathbf 6 , and a threshold voltage of −0.6 V. The hysteresis (0.14 V) of TFT devices confirmed further that the ZITO and HAO films could be the promising candidates for TFT devices. [ABSTRACT FROM PUBLISHER]

The modification of multispin casting multilayered barium titanate (BTO) thin films on indium tin oxide (ITO)/glass substrate without doping other elements is adopted to improve the memory performance. The X-ray photoelectron spectroscopy analysis reveals the concentration of oxygen vacancies can be reduced by the increasing number of the BTO layer. Mechanisms of conducting paths relating to the concentration of oxygen vacancies will also be explicated. The memory devices showed typical bipolar resistive switching behavior and an ON/OFF ratio of over 10^\mathrm \mathbf 6 . The memory devices also exhibited outstanding uniformity. A retention time of over 10^\mathrm \mathbf 5 s without fluctuation at room temperature and 85 °C can be achieved. [ABSTRACT FROM AUTHOR]

Fully transparent and stable resistive switching characteristics in resistive random access memory (RRAM) device consisting of ITO/Ga doped ZnO (GZO)/ZnO/ITO architecture are proposed. The GZO nanorods with well aligned and extremely dense properties are considered as a thin film for RRAM device. The oxygen vacancies can be confined and migrate along grain boundaries in the GZO nanorod film. Therefore, the weakest point for formation and rupture of conductive filament can be limited at the interface between GZO nanorod film and ZnO seeding layer. Compared with ITO/ZnO/ITO device, a significant improvement in the distribution of high resistance state (HRS) and low resistance state (LRS) during resistance switching is demonstrated in the present device. In addition, a high endurance of more than 7000 cycles with the resistance ratios of HRS/LRS about 200 times is achieved in this device. The ITO/GZO/ZnO/ITO device is a good candidate for the transparent RRAM application. [ABSTRACT FROM PUBLISHER]

Flexible memristor is one of the most promising wearable devices for abundant data storage and processing. In this work, interface engineering by inserting the Al2O3 barrier layer is carried out to construct Pt/TiOx/Al2O3/Pt/indium tin oxide (ITO) flexible artificial synapse device. The memristor performance can be maintained even under 1000 times of bending without degradation, demonstrating its excellent mechanical property. With the Al2O3 diffusion barrier layer, the oxygen vacancies (${V}_{\text {o}}$) movement is slowed down for filaments formation and rupture, thus it boosts up the synaptic plasticity, including long-term potentiation/depression, paired-pulse facilitation (PPF), and spike-timing-dependent plasticity (STDP). Moreover, on the basis of the enhanced symmetry and linearity of conductance for Pt/TiOx/Al2O3/Pt/indium tin oxide (ITO) memristor, the neural network simulation for supervised learning presents an online learning pattern recognition, the accuracy can achieve to 91.15%. Overall, the Pt/TiOx/Al2O3/Pt/ITO memristor with excellent flexibility is a promising emulator for biological synapses, which could be beneficial to future flexible memristor-based neuromorphic computing. [ABSTRACT FROM AUTHOR]

The deposition parameters of doped hydrogenated nanocrystalline silicon grown by plasma-enhanced chemical vapor deposition were scanned to obtain highly conductive films. The optimized \p^+ and \n^+ nc-Si:H films were used as injecting layers in the fabrication of Si-rich hydrogenated amorphous silicon nitride (\a-SiNx\:H)-based heterojunction \p^+\in^+ diode. The as-grown diode was subjected to a Joule-heating-assisted forming process (FP) via the application of a high electric field. The modifications in the luminescent, electrical, and structural properties of the diode subsequent to the FP were investigated. Although the energy distribution of electroluminescence remains almost the same when compared with that of the fresh diode, its intensity is enhanced by at least 30 times with an orange-red emission easily perceived by the naked eye. Parallelly, the low field-current density drastically increases, presumably due to the Si-nanocrystallite formation within the \a-SiNx\:H layer. This formation, triggered by the neighboring nanocrystalline-doped layers, was confirmed by the X-ray diffraction measurements indicating the rise in the local temperature during FP. [ABSTRACT FROM AUTHOR]

A simple self-assembling approach with only one nickel shadow mask is developed for flexible transparent thin-film transistors (TFTs) with patterned channel fabrication. An ultralow operation voltage of 1.5 V is realized due to the large specific gate capacitance (1.5 \mu\F/cm^2) of the microporous \SiO2-based solid-electrolyte dielectric. Flexible transparent indium–tin-oxide TFTs exhibit a good performance with a low subthreshold swing of < 70 mV/dec and a large on/off ratio of \sim\!\!\10^7, respectively. Such low-voltage flexible transparent TFTs with a simple self-assembling process are promising for portable flexible transparent electronics applications. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) were incorporated into indium tin oxide and polythiophene by mixing and then spin coating or screen printing to form the transparent conducting electrode (TCE). With only approximately 0.005%, by weight, of CNTs in the TCE, the sheet resistance was found to drop by about 25% to 40%, without any significant decrease in the transmittance. Organic light-emitting devices (OLEDs) were then fabricated using these composite TCEs as the anode. In comparison with a device without the CNTs, there was an increase in the current density for the same applied voltage, mainly due to the contribution of hole current. In addition, the mechanical strength was improved, as seen from bending test of the device. [ABSTRACT FROM AUTHOR]