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- 实验方案
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Temperature-Dependent Phase Transition in Orthorhombic [011]c Pb(Mg1/3Nb2/3) O3-0.35PbTiO3 Single Crystal
摘要： Relaxor [011]c PMN-0.35PT single crystal phase transition characteristics are investigated through various methods including variable temperature dielectric properties, X-ray diffraction, bipolar ferroelectric hysteresis loops (P-E) and electric-field-induced strain (S-E) hysteresis loops measurements. The results reveal that two phase transitions exist within the range from room temperature to 250 °C: orthorhombic (O)-tetragonal (T)-cubic (C). The O-to-T and T-to-C phase transition temperatures have been identified as 84 °C and 152 °C, respectively. Diffuseness degree of the T-to-C phase transition for the unpoled single crystal has been calculated to be 1.56, implying an intermediate state between normal and relaxor ferroelectrics. Temperature-dependent remanent polarization (Pr), coercive field (Ec), saturation polarization (Ps), hysteresis loop squareness (Rsq), and longitudinal piezoelectric constant (d*33) are also explored to learn the details of the phase transitions. Variable temperature unipolar Suni-E hysteresis loops avail additional evidence for the microstructure change in the as-measured single crystal.
关键词： temperature-dependent phase transition,S-E hysteresis loops,P-E hysteresis loops,orthorhombic [011]c PMN-0.35PT,dielectric properties,piezoelectric properties
更新于2025-09-23 15:22:29
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Volatile Memory Characteristics of a Solution-Processed Tin Oxide Semiconductor
摘要： In this paper, we demonstrate and study volatile memory characteristics of the sol-gel SnOx semiconductor. The SnOx exhibits a significant self-rectifying behavior and high nonlinearity. Low reverse-biased currents and high forward-biased currents are observed in the positive and negative voltage regions, respectively. The rectifying ratio can reach 3.7 × 10^5, and the selection ratio (I@Vread/I@0.5Vread) is 10^2. A pinched current hysteresis is found in the forward-biased region, which indicates the volatile memory characteristics of the SnOx memory. The resistance ratio between the high-resistance state (HRS) and low-resistance state (LRS) is ~10^5. In addition, the stability test reveals that the memory can repeatedly operate for over 1.5 × 10^3 cycles.
关键词： Hysteresis,Solution process,Oxide semiconductor,Thin film,Electrical characteristics
更新于2025-09-23 15:22:29
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[ASME ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - San Francisco, California, USA (Monday 27 August 2018)] ASME 2018 International Technical Conference and Exhibition on Packaging and Integration of Electronic and Photonic Microsystems - Microstructural Evolution in SAC305 and SAC-Bi Solders Subjected to Mechanical Cycling
摘要： Fatigue failure of solder joints is one of the most common methods by which electronic packages fail. Electronic assemblies usually must cope with a temperature varying environment. Due to the mismatches in coefficients of thermal expansion (CTEs) of the various assembly materials, the solder joints are subjected to cyclic thermal-mechanical loading during temperature cycling. The main focus of this work is to investigate the changes in microstructure that occur in SAC305 and SAC+Bi lead free solders subjected to mechanical cycling. In this paper, we report on results for the SAC+Bi solder commonly known as SAC_Q or CYCLOMAX. Uniaxial solder specimens were prepared in glass tubes, and the outside surfaces were polished. A nanoindenter was then used to mark fixed regions on the samples for subsequent microscopy evaluation. The samples were subjected to mechanical cycling, and the microstructures of the selected fixed regions were recorded after various durations of cycling using Scanning Electron Microscopy (SEM). Using the recorded images, it was observed that the cycling induced damage consisted primarily of small intergranular cracks forming along the subgrain boundaries within dendrites. These cracks continued to grow as the cycling continued, resulting in a weakening of the dendrite structure, and eventually to the formation of large transgranular cracks. The distribution and size of the intermetallic particles in the inter-dendritic regions were observed to remain essentially unchanged.
关键词： Bismuth,Microstructure,SAC Alloy,Hysteresis,Evolution,Lead Free Solder,Cyclic Stress-Strain Curve
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe) - Palermo (2018.6.12-2018.6.15)] 2018 IEEE International Conference on Environment and Electrical Engineering and 2018 IEEE Industrial and Commercial Power Systems Europe (EEEIC / I&CPS Europe) - Nonlinear Multi-Scale Dynamics Modeling of a Piezoelectric Energy Harvester
摘要： Hysteretic effects play a crucial role in the behavior of devices based on piezoelectric materials. Most of the research focuses on modeling these effects for controlling the dynamic response of piezoelectric actuators. Few studies discuss how hysteresis influences power generation and performances of energy harvesters based on such active materials. In this paper, a recently developed physics-based model of a PZT crystal is employed to assess the effects of material mesoscopic variables on the macroscopic response of a piezoelectric energy harvester modeled as a SDOF system. A multi-scale approach is adopted where, at the mesoscale, crystal domain switching - the source of hysteretic behavior - is taken into account through a probabilistic thermodynamic approach. Effects of hysteretic nonlinearities on harvesting performances of the considered device are investigated by means of simulations. A comparison between predictions of two models - with and without hysteresis - is also reported.
关键词： Piezoelectric,Hysteresis,Energy harvesting,Nonlinear Multi-scale Dynamics
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Kyoto, Japan (2018.6.21-2018.6.22)] 2018 IEEE International Meeting for Future of Electron Devices, Kansai (IMFEDK) - Study on Threshold Voltage Hysteresis in GaN-Based Vertical Trench MOSFETs
摘要： In this paper, we studied hysteresis in transfer characteristics of GaN-based vertical trench MOSFETs fabricated using different process technologies for n+-GaN source layer. It was found that the device with epitaxially-grown source region can suppress hysteresis in the transfer characteristics compared to that with implanted source region.
关键词： ion implantation,threshold voltage,epitaxial growth,hysteresis,GaN,trench,MOSFET
更新于2025-09-23 15:22:29
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A non-isothermal phase-field model for piezo–ferroelectric materials
摘要： We propose a model for the study of piezo–ferroelectric materials, based on the Ginzburg–Landau approach to the ferroelectric transition, in which the inelastic deformation is a direct function of the ferroelectric polarization. The non-isothermal effects related to the phase change and other dissipative phenomena are considered by a suitable energy balance equation, according to the restrictions of the second principle. The hysteresis phenomena for polarization and inelastic strain are considered from both the energetic perspective of the vector Ginzburg–Landau equation and the dissipation-dominated perspective of the rate-independent evolutionary equations.
关键词： Ferroelectric,Phase field,Ferroelastic,Non-isothermal model,Hysteresis
更新于2025-09-23 15:22:29
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[IEEE 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Shenzhen, China (2018.6.6-2018.6.8)] 2018 IEEE International Conference on Electron Devices and Solid State Circuits (EDSSC) - Characterization of Transient Threshold Voltage Shifts in Enhancement- and Depletion-mode AlGaN/GaN Metal-Insulator-Semiconductor (MIS)-HEMTs
摘要： Both enhancement- and depletion-mode AlGaN/GaN metal-insulator-semiconductor HEMTs were fabricated with Al2O3 as the gate dielectric formed by atomic layer deposition (ALD). With the common problems of threshold voltage hysteresis in AlGaN/GaN MIS-HEMTs, DC I-V and fast transient frequency-dependent C-V measurements were performed to characterize the threshold voltage shifts ?Vth and hence to systematically study the underlying mechanism. The experimental results reveal that ?Vth can be as high as 1.0 V at VG,max = 5 V in transient I-V measurements despite the much lower values of 0.42 V in static and CV measurements. This has significant implications in using AlGaN/GaN MIS-HEMTs for high voltage switching applications. Besides, multi-frequency C-V measurements show that the primary ?Vth is frequency independent but the second onset of voltage shifts (?V2) shows obvious frequency dependence. These results imply the likely mechanism of slow (deep) Al2O3 interface traps accounting for ?V1 hysteresis, and fast (shallow) interface traps accounting for ?V2.
关键词： AlGaN/GaN MIS-HEMT,Al2O3/III-N interface traps (fast and slow) and threshold voltage hysteresis.
更新于2025-09-23 15:21:21
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Reducing Anomalous Hysteresis in Perovskite Solar Cells by Suppressing Interfacial Ferroelectric Order
摘要： Despite booming researches in organometal halide perovskite solar cells (PSCs) of recent years, considerable roadblocks remain for their large-scale deployment, ranging from undesirable current-voltage hysteresis to inferior device stability. Among various plausible origins of the hysteresis, interfacial ferroelectricity is particularly intriguing and warrants a close scrutiny. Here, we examine interfacial ferroelectricity in MAPbI3 (FAPbI3)/TiO2 and MAPbI3/PCBM heterostructures, and explore the correlations between the interfacial ferroelectricity and the hysteresis from the perspective of nonadiabatic electronic dynamics. It is found that ferroelectric order develops at the MAPbI3/TiO2 interface owing to the interaction between the polar MA ions and TiO2. The polarization switching of the MA ions under an applied gate field would result in drastically different rates in interfacial photoelectron injection and electron-hole recombination, contributing to the undesirable hysteresis. In a sharp contrast, ferroelectricity is suppressed at the FAPbI3/TiO2 and MAPbI3/PCBM interfaces, thanks to elimination of the interfacial electric field between perovskite and TiO2 via substitution of strong polar MA (dipole moment: 2.29 Debye) by weak polar FA ions (dipole moment: 0.29 Debye) and interface passivation, leading to consistent interfacial electronic dynamics and the absence of the hysteresis. The present work sheds light to the physical cause for hysteresis and points to the direction to which the hysteresis could be mitigated in PSCs.
关键词： Ferroelectricity,Hysteresis,Perovskite Solar Cells,Excited-state Electronic Dynamics,Electron-Hole Recombination,Orientation Selectivity
更新于2025-09-23 15:21:01
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Performance Improvement of Gate-Tunable Organic Light-Emitting Diodes with Electron-Transport and Hole-Blocking Layers
摘要： The current density and luminance of gate-tunable organic light-emitting diodes (OLEDs) can be modulated by application of an external gate potential. However, existing gate-tunable OLEDs require further optimization to make them suitable for practical use. In this work, the rapid electron conduction of 4,4’-bis(N-carbazolyl)-1,1’biphenyl (CBP) molecules under low operating potential is demonstrated in polymer electrolyte-coated super yellow (SY) polymer light-emitting diodes (PLEDs). This behavior is attributed to the facile electrochemical n-doping of CBP by the polymer electrolyte infiltrated into the SY PLED through the porous aluminum cathode. The field-modulated conductivity of CBP upon applying an external gate potential to electrolyte-gated (EG) PLEDs is demonstrated. These phenomena lead to the improved performance of EG SY PLEDs with a CBP electron-transport layer and 1,3,5-tris[(3-pyridyl)-phen-3-yl]benzene) (TmpypB) hole-blocking layer between the porous aluminum cathode and SY emissive layer, including low turn-on voltage (1.5 V), low current density leakage (0.01 mA/cm2), low off luminance (<0.01 cd/m2), saturated on-current density (2 mA/cm2) and on-luminance (100 cd/m2), and largely suppressed hysteresis. These results pave the path for practical application of EG OLEDs in displays, especially near-to-eye displays.
关键词： facile electrochemical doping,saturated on-current density and on-luminance,low off-current density leakage and off-luminance,suppressed hysteresis,near-to-eye displays,gate-tunable organic light-emitting diodes,grayscale displaying,porous electrodes
更新于2025-09-23 15:21:01
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Alkali Metal Ions: A Secret Ingredient for Metal Nanocluster-Sensitized Solar Cells
摘要： The presence of alkali metal ions (AMIs) during the adsorption of thiolated Au nanoclusters (NCs) onto TiO2 plays a critical role in achieving high power conversion efficiency and suppressing anomalous current?voltage hysteresis in metal nanocluster-sensitized solar cells. This hidden role of the AMIs is intimately related to the adsorption strength between the NCs and TiO2, indicating the importance of seeking a comprehensive understanding of NC?TiO2 interfaces and devising interfacial engineering techniques to support the next advance in light energy conversion applications of NCs.
关键词： alkali metal ions,metal nanoclusters,current?voltage hysteresis,power conversion efficiency,solar cells
更新于2025-09-23 15:21:01