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Resistance-switching properties of Bi-doped $$\hbox {SrTiO}_{3}$$SrTiO3 films for non-volatile memory applications with different device structures
摘要： SrTiO3 and Bi-doped SrTiO3 ?lms were fabricated with different device structures using the sol–gel method for non-volatile memory applications, and their resistance-switching behaviour, endurance and retention characteristics were investigated. SrTiO3 and Sr0.92Bi0.08TiO3 ?lms grown on Si or Pt have the same phase structure, morphologies and grain size; however, the grain size of the Sr0.92Bi0.08TiO3 ?lms grown on Si is slightly larger than those of the SrTiO3 ?lms grown on Si and the Sr0.92Bi0.08TiO3 ?lms grown on Pt. The SrTiO3 or Sr0.92Bi0.08TiO3 ?lms grown on Si or Pt all exhibit bipolar resistive-switching behaviour and follow the same conductive mechanism; however, the Ag/Sr0.92Bi0.08TiO3/Si device possesses the highest RHRS/RLRS of 105 and the best endurance and retention characteristics. The doping of Bi is conducive to enhance the RHRS/RLRS of the SrTiO3 ?lms; meanwhile, the Si substrates help improve the endurance and retention characteristics of the Sr0.92Bi0.08TiO3 ?lms.
关键词： SrTiO3,resistance-switching properties,Bi doping,device structure,sol–gel
更新于2025-09-04 15:30:14
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A brief overview of RF sputtering deposition of boron carbon nitride (BCN) thin films
摘要： A great part of interest has been paid for fabricating new materials with novel mechanical, optical, and electrical properties. Boron carbon nitride (BCN) ternary system was applied for variable bandgap semiconductors and systems with extreme hardness. The purpose of this literature review is to provide a brief historical overview of B4C and BN, to review recent research trends in the BCN synthesizes, and to summarize the fabrication of BCN thin films by plasma sputtering technique from B4C and BN targets in different gas atmospheres. Pre-set criteria are used to discuss the processing parameters affecting BCN performance which includes the gasses flow ratio and effect of temperature. Moreover, many characterization studies such as mechanical, etching, optical, photoluminescence, XPS, and corrosion studies of the RF sputtered BCN thin films are also covered. We further mentioned the application of BCN thin films to enhance the electrical properties of metal-insulator-metal (MIM) devices according to a previous report of Prakash et al. (Opt. Lett. 41, 4249, 2016).
关键词： Radio frequency sputtering,Gas flow ratio,Boron carbon nitride,Metal-insulator-metal device
更新于2025-09-04 15:30:14
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Low Power Stretchable Active-Matrix Red, Green, Blue (RGB) Electrochromic Device Array of Poly(3-methylthiophene)/Prussian blue
摘要： We report the fabrication of a stretchable array of active-matrix (AM) electrochromic devices (ECDs). The ECD is made of poly(3-methylthiophene) and Prussian blue electrodes with a mixed gel electrolyte of acetonitrile, poly(methyl methacrylate), propylene carbonate, and lithium perchlorate. The ECD displays can express red, green, or blue (RGB) depending on the applied voltage and has a high stability in air. It exhibits low power consumption levels of 331 and 378 μW cm-2 (10 s duration) at -1.0 and 1.0 V, respectively, and a high coloration efficiency of 201.6 cm2 C-1 at 1.0 V. A 4 × 4 AM ECD array is integrated on a deformable Ecoflex substrate via a dry transfer method using patterned liquid metal-interconnections. The display shows a mechanical stability under bending and biaxial stretching by 30%. Finite element method analysis of the strain distribution also confirms that strain is not applied to the ECDs, guaranteeing stable operation of the array under deformation. Furthermore, a stretchable 6 × 6 AM ECD array for higher resolution display also exhibits mechanical stability under 30% biaxial stretching. This work demonstrates the high potential of our stretchable ECD array in low power-consuming displays for stretchable electronics, wearable devices, and electronic skin.
关键词： electrochromic device,active-matrix display,stretchable electronics,poly(3-methylthiophene),prussian blue
更新于2025-09-04 15:30:14
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Exciton-Induced Degradation of Hole Transport Layers and Its Effect on the Efficiency and Stability of Phosphorescent Organic Light-Emitting Devices
摘要： The effect of exciton-induced degradation of hole transport layers (HTLs) and its influence on efficiency and stability of phosphorescent organic light emitting devices (PhOLEDs) are investigated. In order to be able to isolate and study the effect of excitons on HTLs, UV illumination as a means to expose them to exciton stress is used. Results reveal that exciton stress of only the HTLs can lead to a significant deterioration in the electroluminescence external quantum efficiency and stability of PhOLEDs, revealing the detrimental role of exciton-induced degradation of HTLs in limiting the device performance. The creation of quenchers in HTLs and the diffusion of excitons from the HTL to the EML appear to play roles in this degradation mechanism. Observations reveal that exciton-induced degradation of HTLs more strongly impacts PhOLEDs than their fluorescent counterparts, revealing the more critical role that HTLs play in influencing their stability and pointing to the role of triplet excitons in this phenomenon. Observations also suggest that increasing the exciton stability of HTLs or reducing exciton lifetime in them can help increase device stability. The findings uncover a new degradation mode in PhOLEDs and provide key insights for device design for realizing better performance and stability.
关键词： electroluminescence efficiency,device stability,phosphorescent OLEDs,exciton-induced degradation,hole transport layers
更新于2025-09-04 15:30:14
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Multi-probe ptychographic iterative engine method
摘要： As a lensfree imaging technique, ptychographic iterative engine (PIE) can provide quantitative amplitude and phase distributions of samples in an extremely large field of view but without aberrations. However, relying on the single pinhole scanning, PIE is time-consuming in both diffraction recording and sample reconstruction, thus limiting its potentiality in dynamic imaging applications. In order to reduce the diffraction captures and increase its processing efficiency, we design the multi-probe PIE, in which a pinhole array is adopted instead of traditionally used single pinhole, thus diffractions at different positions can be captured simultaneously. Moreover, the multi-probe PIE reconstruction algorithm is also implemented to further accelerate the sample reconstruction speed. Proved by experiments, less than 10 s is required for diffraction recording for a large field of view of ~150 mm2, and combining with the modified multi-probe PIE reconstruction algorithm, high-resolution quantitative sample information can be extracted accurately with much faster speed compared to traditional PIE reconstruction algorithm. It is believed the proposed multi-probe PIE can be future applied in dynamic imaging.
关键词： Quantitative imaging,Ptychographic iterative engine,Digital micro-mirror device
更新于2025-09-04 15:30:14
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The Effects of Thermal Neutron Irradiation on Current-Voltage and Capacitance-Voltage Characteristics of Au/n-Si/Ag Schottky Barrier Diodes
摘要： To observe the neutron transmutation and displacement damage effects, Au/n-Si/Ag Schottky barrier diodes were exposed to thermal neutron irradiation. Irradiation induced changes in Schottky barrier height, saturation current, and donor concentration were investigated by using current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the diodes. The irradiation for 10 s caused a little change in the Schottky diode parameters which were obtained from I-Vand C-V measurements. Observable changes in the parameters occurred after the second irradiation of 30 s duration. After the total dose, an increase in saturation current and barrier height inhomogeneties took into place and a decrease in carrier concentration was observed due to the carrier removal effect of thermal neutron-induced damages. Whereas the values of zero bias barrier height have little change after irradiations, the values of ideality factor increased after irradiations. The values of zero-bias barrier height for all diodes was also calculated from reverse bias current characteristics. After second dose, the values of zero-bias barrier height decreased for all diodes. The values of series resistance were determined by Cheung functions before and after irradiations. Before irradiations, the values were found between 2.10 kΩ and 2.76 kΩ. After second dose, the values of series resistance of all diodes decreased and were found between 1.59 kΩ and 2.20 kΩ. Furthermore, the proof of thermal neutron transmu- tation of elements in the devices was given via energy dispersive spectroscopy (EDS) mapping.
关键词： Semiconductor device radiation effects,Schottky diode,Electrical characterization,EDS mapping,Silicon,Thermal neutron irradiation
更新于2025-09-04 15:30:14
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Highly uniform electrochromic tungsten oxide thin films deposited by e-beam evaporation for energy saving systems
摘要： In the last few decades, there has been a surge of interest in using tungsten oxide thin films as an active layer of electrochromic device. These devices have several practical applications such as smart window of buildings and automobile glazing for energy saving. The main objective of this work was to construct highly homogeneous and uniform e-beam evaporated amorphous WO3-x based films into electrochromic devices, which were fully characterized for switching speed, coloration efficiencies and cycling voltammetry responses. Fabricated devices contain indium doped transparent oxide coated glass as the transparent conductive electrode, ～200 nm thickness of WO3-x as the cathodically coloring material and a lithium perchlorate based conducting gel electrolyte. X-ray diffraction patterns indicate that all as-deposited films are amorphous. Experimental results showed that both solid and liquid electrolyte electrochromic devices are initially very transparent that exhibit perfect optical modulation and coloration efficiency (up to 68.7 cm2/C and 52.6 cm2/C at 630 nm, respectively) due to easier intercalation of the Li+ within their structure. One of the more significant findings to emerge from this study is that e-beam coated electrochromic devices based on tungsten oxide thin films showed superior performance among to other coating methods. Therefore, excellent reversibility of color change behavior is attractive for pertinent use in electrochromic energy storage devices.
关键词： Thin film,Tungsten oxide,Electrochromic device,Electron-beam evaporation
更新于2025-09-04 15:30:14
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Real-Time Optronic Beamformer on Receive in Phased Array Radar
摘要： The development of phased array radar beamforming technologies has led to an ever-increasing demand for large antenna arrays and multiple beams. However, real-time processing becomes a difficulty for large array or multibeam beamforming due to huge data amount. To overcome the electronic mass data processing speed limitations, optronic technique is developed for beamforming in this letter. We present a novel real-time multibeam optronic beamforming (OPBF) system specially designed for large phased array. In our system design, beamforming is formulated as a finite-impulse response filtering process, of which radar raw data and weighting coefficients are encoded onto the laser beam by joint amplitude and phase control (JAPC) modules and two-dimension adding is performed by a lens. Ultrafast optical calculation and the proposed high-speed JAPC module make the system powerful for real-time processing. The proposed system has good expansibility in data capacity, which makes it applicable to massive data processing. What’s more, a practical low-power optronic beamformer is demonstrated. Measured results show that the presented OPBF system is able to accurately synthesize flexible and controllable multibeams and performs well in channel equalization.
关键词： phase modulation,digital micromirror device (DMD),optronic processing,Amplitude modulation,real-time processing,beamforming
更新于2025-09-04 15:30:14
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Industrial View of III-V Devices Compact Modeling for Circuit Design
摘要： This paper presents a commercial or industrial view of III–V compact models for circuit design. We contrast the requirements of III–V modeling to those of silicon. The differences in requirements are strongly rooted in the applications that III–V devices are used in the end user of III–V models and the differences in the “ecosystems” of the technologies. These differences create both challenges and opportunity for the III–V modeling community.
关键词： semiconductor device modeling,integrated circuit modeling,HEMTs,heterojunction bipolar transistor
更新于2025-09-04 15:30:14
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Iridium oxide catalyst for hybrid electrochromic device based on tetramethylthiourea (TMTU) redox electrolyte
摘要： This work reports a study on sputter coated iridium oxide film as a counter electrode (CE) for the electrochemical catalysis of tetramethylthiourea/tetramethylformaminium disulfide (TMTU/TMFDS2+) redox reaction in electrochromic (EC) devices. The iridium oxide (IrOx) with the thickness of about 5 nm coated onto transparent conductive oxide, e.g., fluorine-doped tin oxide (F:SnO2), has shown excellent catalytic properties and excellent electrochromic cycling stability in EC device. The electrochemical impedance spectroscopy (EIS) results revealed that the charge transfer resistance (Rct) is mainly influenced by the oxygen flow rate during the sputtering process, and by the layer thickness. The IrOX films coated with low oxygen flow rate has shown a lower charge transfer resistance compared to the fully oxidized iridium oxide film. However, sub-stoichiometric layers are less transparent, and therefore less appropriate for the application. In this regard, fully oxidized and highly transparent (Tvisible = 86%) layer formed by the sputtering process at or above 50 sccm (standard cubic centimeters per minute) flow of oxygen having the thickness of 5 nm is used in EC devices. These layers have the Rct of 25 Ω cm2 at 1 V bias voltage for the redox electrolytes. The cyclic voltammetry technique has shown a typical quasi-reversible nature of redox electrolyte at the same IrOx coated electrode. An electrochromic test for 550 cycles demonstrates that 5 nm of IrOx is sufficient for the stabile EC window with TMTU/TMFDS2+ electrolyte.
关键词： Sputter coating,Redox electrolyte,Iridium oxide,Electrochromic device,Tetramethylthiourea
更新于2025-09-04 15:30:14