Device Structure Research Articles

FS-iTFET: advancing tunnel FET technology with Schottky-inductive source and GAA design

In this paper, we introduce a novel Forkshape nanosheet Inductive Tunnel Field-Effect Transistor (FS-iTFET) featuring a Gate-All-Around structure and a full-line tunneling heterojunction channel. The overlapping gate and source contact regions create a strong and uniform electric field in the channel. Furthermore, the metal–semiconductor Schottky junction in the intrinsic source region induces the required carriers without the need for doping. This innovative design achieves both a steeper subthreshold swing (SS) and a higher ON-state current (ION). Using calibration-based simulations with Sentaurus TCAD, we compare the performance of three newly designed device structures: the conventional Nanosheet Tunnel Field-Effect Transistor (NS-TFET), the Nanosheet Line-tunneling TFET (NS-LTFET), and the proposed FS-iTFET. Simulation results show that, compared to the traditional NS-TFET, the NS-LTFET with its full line-tunneling structure improves the average subthreshold swing (SSAVG) by 19.2%. More significantly, the FS-iTFET, utilizing the Schottky-inductive source, further improves the SSAVG by 49% and achieves a superior ION/IOFF ratio. Additionally, we explore the impact of Trap-Assisted Tunneling on the performance of the three different integrations. The FS-iTFET consistently demonstrates superior performance across various metrics, highlighting its potential in advancing tunnel field-effect transistor technology.

Atomic Layer-Deposited Silane Coupling Agent for Interface Passivation of Quantum Dot Light-Emitting Diodes.

Inserting an insulating layer between the charge transport layer (CTL) and quantum dot emitting layer (QDL) is widely used in improving the performance of quantum dot light-emitting diodes (QLEDs). However, the additional layer inevitably leads to energy loss and joule heat. Herein, a monolayer silane coupling agent is used to modify the said interfaces via the self-limiting adsorption effect. Because the ultrathin layers induce negligible series resistance to the device, they can partially passivate the interfacial defects on the electron transport side and help confine the electrons within the QDL on the hole transport side. These interfacial modifications can not only suppress the nonradiative recombination but also slow down the aging of the hole transport layer. The findings here underline a low-temperature adsorption-based strategy for effective interfacial modification which can be used in any layer-by-layer device structures.

Ligand‐Solvent Coordination Enables Comprehensive Trap Passivation for Efficient Near‐Infrared Quantum Dot Light‐Emitting Diodes

AbstractNear‐infrared light‐emitting diodes (NIR LEDs) based on perovskite quantum dots (QDs) have produced external quantum efficiency (EQE) of ~15 %. However, these high‐performance NIR‐QLEDs suffer from immediate carrier quenching because of the accumulation of migratable ions at the surface of the QDs. These uncoordinated ions and carriers—if not bound to the nanocrystal surface—serve as centers for exciton quenching and device degradation. In this work, we overcome this issue and fabricate high‐performance NIR QLEDs by devising a ligand anchoring strategy, which entails dissolving the strong‐binding ligand (Guanidine Hydroiodide, GAI) in the mediate‐polar solvent. By employing the dye‐sensitized device structure (phosphorescent indicator), we demonstrate the elimination of the interface defects. The treated QDs films exhibit an exciton binding energy of 117 meV: this represents a 1.5‐fold increase compared to that of the control (74 meV). We report, as a result, the NIR QLEDs with an EQE of 21 % which is a record among NIR perovskite QLEDs. These QLEDs also exhibit a 7‐fold higher operational stability than that of the best previously reported NIR QLEDs. Furthermore, we demonstrate that the QDs are compatible with large‐area QLEDs: we showcase 900 mm2 QLEDs with EQE approaching 20 %.

Biomass Derived Self-Doped Carbon Nanosheets Enable Robust Hole Transport Layers with Ion Buffer for Perovskite Solar Cells.

The diffusion of iodine species and lead leakage during device degradation represent the main obstacles restricting the commercial application of perovskite solar cells (PSCs). Cobalt loaded ultrathin carbon nanosheets (Co(III)-CNS) derived from biomass are prepared as ion buffer material to construct robust hole transport layers (HTLs). The carbon nanosheets containing trivalent cobalt ions can facilitate the oxidation of the hole transport material while preserving the structural integrity and electrical properties of HTLs under thermal stress, thereby ensuring efficient carrier transport. The two-dimensional ultrathin graphitized lamellar structure of Co(III)-CNS is conducive to alleviate the corrosive effects of the outward diffusion of iodine species on HTLs and silver electrodes, while avoiding irreversible degradation of PSCs. With the improvement of HTL composition and the related interfaces, Co(III)-CNS doped devices can maintain intact device structure under thermal stress and remain above 80% of the original power conversion efficiency (PCE) after thermal aging at 85 oC for 720 h. Notably, the chemical interactions between heteroatoms of self-doped carbon nanosheets and the mobile lead ions can effectively alleviate lead leakage and avoid the potential impacts of device degradation on ecosystem. Ultimately, the Co(III)-CNS doped PSCs with enhanced thermal stability exhibit a champion PCE of 22.32%.

Single-Molecule White Circularly Polarized Photoluminescence and Electroluminescence from Dual-Emission Enantiomers.

The strategy of integrating conformational isomerization donors and chiral acceptors in a single molecule was proposed to construct white circularly polarized luminescence (WCPL) materials in this work. Consequently, a pair of dual-emission enantiomers, namely (R/S)-DO-PTZ, were designed and synthesized, which displayed white emission with blue and yellow dual-emission bands in solution and solid films with Commission Internationale de l'Eclairage (CIE) coordinates of (0.30, 0.33) and (0.33, 0.35), respectively. Meanwhile, (R/S)-DO-PTZ exhibited a high PLQY of up to 67 % in doped films and clear mirror-image WCPL signals with a |glum| value of 3.0×10-3. Moreover, white circularly polarized electroluminescence (WCPEL) based on organic light-emitting diodes (OLEDs) with (R/S)-DO-PTZ as emitters were also achieved with CIE coordinates of (0.32, 0.37) and EQEmax of 4.7 %, representing the state-of-the-art level of white OLEDs based on single-molecule purely organic emitters. By optimizing the device structure, warm WCPEL devices were further obtained with a |gEL| value of 2.8×10-3, CIE coordinates of (0.37, 0.48) and EQEmax of up to 15.6 %. To our knowledge, this is the first report of CP-WOLEDs based on single-molecule purely organic emitters.

Ligand-Solvent Coordination Enables Comprehensive Trap Passivation for Efficient Near-Infrared Quantum Dot Light-Emitting Diodes.

Near-infrared light-emitting diodes (NIR LEDs) based on perovskite quantum dots (QDs) have produced external quantum efficiency (EQE) of ~15 %. However, these high-performance NIR-QLEDs suffer from immediate carrier quenching because of the accumulation of migratable ions at the surface of the QDs. These uncoordinated ions and carriers-if not bound to the nanocrystal surface-serve as centers for exciton quenching and device degradation. In this work, we overcome this issue and fabricate high-performance NIR QLEDs by devising a ligand anchoring strategy, which entails dissolving the strong-binding ligand (Guanidine Hydroiodide, GAI) in the mediate-polar solvent. By employing the dye-sensitized device structure (phosphorescent indicator), we demonstrate the elimination of the interface defects. The treated QDs films exhibit an exciton binding energy of 117 meV: this represents a 1.5-fold increase compared to that of the control (74 meV). We report, as a result, the NIR QLEDs with an EQE of 21 % which is a record among NIR perovskite QLEDs. These QLEDs also exhibit a 7-fold higher operational stability than that of the best previously reported NIR QLEDs. Furthermore, we demonstrate that the QDs are compatible with large-area QLEDs: we showcase 900 mm2 QLEDs with EQE approaching 20 %.

Non-invasive follow-up for intracranial aneurysms treated with contour neurovascular system-comparison of digital subtraction angiography (DSA) to magnetic resonance imaging (MRI) and spectral computed tomography angiography (CTA) in vitro.

The contour neurovascular system (CNS) is an intrasaccular flow-disrupting device designed for the treatment of intracranial wide-necked bifurcation aneurysms. Metal artifacts limit magnetic resonance imaging (MRI) accessibility after implantation. The purpose of this in vitro study was to evaluate non-invasive imaging alternatives to digital subtraction angiography (DSA). Three aneurysms of patients originally treated with CNS were three-dimensional (3D)-printed (one at the basilar tip and two at the middle cerebral artery bifurcation). CNS devices were implanted under fluoroscopic control into the 3D models. Post-implantation two-dimensional-DSA, flat panel computed tomography angiography (CTA), MRI, and spectral CTA were performed. Time of flight angiography and T1 weighted sequences showed large susceptibility artifacts at the detachment zone of the devices. A thin-sliced T2 weighted sequence in cross-sectional orientation to the aneurysm allowed visualization of the aneurysm dome, but the aneurysm neck and parent vessel could not be assessed. Focused spectral CTA, especially a 40 keV reconstruction with a metal artifact reduction algorithm (orthopedic metal artifact reduction (OMAR)), showed only minor artifacts at the detachment zone. This approach achieved a very similar result to DSA and flat panel computed tomography, enabling the assessment of the device structure, aneurysm perfusion, and parent vessel perfusion. For non-invasive follow-up of CNS, focused 40 keV CTA with OMAR seems to be a valuable option. MRI can be valuable for larger aneurysms to assess the aneurysm dome, but was not suitable for evaluating the parent vessels and aneurysm neck after CNS implantation in this study.

Co-adsorbed self-assembled monolayer enables high-performance perovskite and organic solar cells

Self-assembled monolayers (SAMs) have become pivotal in achieving high-performance perovskite solar cells (PSCs) and organic solar cells (OSCs) by significantly minimizing interfacial energy losses. In this study, we propose a co-adsorb (CA) strategy employing a novel small molecule, 2-chloro-5-(trifluoromethyl)isonicotinic acid (PyCA-3F), introducing at the buried interface between 2PACz and the perovskite/organic layers. This approach effectively diminishes 2PACz’s aggregation, enhancing surface smoothness and increasing work function for the modified SAM layer, thereby providing a flattened buried interface with a favorable heterointerface for perovskite. The resultant improvements in crystallinity, minimized trap states, and augmented hole extraction and transfer capabilities have propelled power conversion efficiencies (PCEs) beyond 25% in PSCs with a p-i-n structure (certified at 24.68%). OSCs employing the CA strategy achieve remarkable PCEs of 19.51% based on PM1:PTQ10:m-BTP-PhC6 photoactive system. Notably, universal improvements have also been achieved for the other two popular OSC systems. After a 1000-hour maximal power point tracking, the encapsulated PSCs and OSCs retain approximately 90% and 80% of their initial PCEs, respectively. This work introduces a facile, rational, and effective method to enhance the performance of SAMs, realizing efficiency breakthroughs in both PSCs and OSCs with a favorable p-i-n device structure, along with improved operational stability.

Energy dissipation methods and protection device synergy strategies for offshore wind power receiving end surplus power

Abstract Firstly, a theoretical analysis of the fault ride-through scheme is carried out based on the land-side AC faults in the offshore wind power delivery system. According to the topological structure of the DC energy consumption device, the working mode and switching of the DC energy consumption device are analyzed and studied. Secondly, the DC protection action of offshore wind power flexible and direct transmission systems was studied, and the switching strategy of energy-consuming devices was determined. Then the impact of the switching of the energy-consuming device on the DC protection function was studied, focusing on the synergy between the DC overvoltage protection and the switching judgment voltage of the energy-consuming device. Finally, based on a typical offshore wind power flexing project, a system model is built in PSCAD/EMTDC to verify the effectiveness of the proposed synergy strategy.

Research on new structure of high voltage 4H-SiC power UMOSFET devices

Research on new structure of high voltage 4H-SiC power UMOSFET devices

Research on anti-single event ability and reinforcement method of SiC MOSFET

Abstract High-voltage silicon carbide (SiC) metal-oxide field-effect transistor (MOSFET) is limited by its ability to resist single event effect (SEE), so it is necessary to study its ability to resist SEE and form an effective reinforcement method. In this paper, it will be studied that how the influence of device structure on the anti-single event ability of SiC MOSFET from the irradiation experiment, and the safe working area of single event leakage degradation of the device is examined. It is found that the width of junction field effect transistor (JFET) and P- type ohmic contact interval both affect the SEE of the device. The SEE mechanism of the device is analyzed based on the experimental results. And the failure caused by local electrothermal stress concentration is confirmed. In view of this mechanism, the reinforced structure is designed with SiO2 barrier layer added in the single event sensitive area, the electrical stress is effectively alleviated, and the peak drain current is reduced by about 18%.

Performance optimization of (FA)2BiCuI6 perovskite solar cells using transport layer integration

The double-halide perovskite (FA)₂BiCuI₆ has been identified as a key material for enhancing the light absorption in perovskite solar cells (PSCs). In a device structure composed of FTO/STO/(FA)₂BiCuI₆/Spiro-OMeTAD/Au, notable photovoltaic (PV) performance has been achieved. Sulfur-doped tin oxide (STO) is utilized as the electron transport layer (ETL), (FA)₂BiCuI₆ serves as the absorber, and Spiro-OMeTAD functions as the hole transport layer (HTL), with gold (Au) and fluorine-doped tin oxide (FTO) acting as the contacts. Through optimization using the Solar Cell Capacitance Simulator (SCAPS-1D), the thicknesses of the absorber, HTL, ETL, and FTO were set to 1000 nm, 150 nm, 150 nm, and 100 nm, respectively, with the device operating at 300 K. This setup demonstrated high performance under the AM1.5 G spectrum, yielding an open-circuit voltage (VOC) of 1.02 V, a short-circuit current density (JSC) of 25.6 mA/cm², a fill factor (FF) of 87.76 %, and a power conversion efficiency (PCE) of 22.97 %. The device also exhibited a quantum efficiency (QE) of approximately 99.30 % within the visible light range.

Enhanced breakdown voltage for p-GaN gate AlGaN/GaN HEMT on AlN/Si with triple trenches: A simulation study

This study presents an analysis of an AlGaN/GaN high-electron-mobility transistor (HEMT) with a triple-trench structure (TT-HEMT) for the enhancement of breakdown voltage, which is often limited by the high electric field near the gate edge. Using COMSOL Multiphysics, simulations were run, with trenches made of gallium nitride (GaN) constructed between the GaN and aluminum nitride (AlN) nucleation layers. Each trench was positioned directly beneath the source, gate, and drain contacts. Under the metal gate, a p-type doped GaN cap is added to produce an enhancement mode device, which is more desirable in high-power applications. The results indicate that the effective dispersion of the electric field distribution enhances the breakdown voltage of the device by 70 % in comparison to a conventional HEMT. Additionally, the impact of various design parameters, such as the p-GaN doping concentration and the metal gate work function on the electrical performance, was also investigated. Overall, the proposed device structure exhibits superior electrical properties for high-power applications.

Hardware-Efficient Configurable Ring-Oscillator-Based Physical Unclonable Function/True Random Number Generator Module for Secure Key Management.

The use of physical unclonable functions (PUFs) linked to the manufacturing process of the electronic devices supporting applications that exchange critical data over the Internet has made these elements essential to guarantee the authenticity of said devices, as well as the confidentiality and integrity of the information they process or transmit. This paper describes the development of a configurable PUF/TRNG module based on ring oscillators (ROs) that takes full advantage of the structure of modern programmable devices offered by Xilinx 7 Series families. The proposed architecture improves the hardware efficiency with two main objectives. On the one hand, we perform an exhaustive statistical characterization of the results derived from the exploitation of RO configurability. On the other hand, we undertake the development of a new version of the module that requires a smaller amount of resources while considerably increasing the number of output bits compared to other proposals previously reported in the literature. The design as a highly parameterized intellectual property (IP) module connectable through a standard interface to a soft- or hard-core general-purpose processor greatly facilitates its integration into embedded solutions while accelerating the validation and characterization of this element on the same electronic device that implements it. The studies carried out reveal adequate values of reliability, uniqueness, and unpredictability when the module acts as a PUF, as well as acceptable levels of randomness and entropy when it acts as a true random number generator (TRNG). They also illustrate the ability to obfuscate and recover identifiers or cryptographic keys of up to 4096 bits using an implementation of the PUF/TRNG module that requires only an array of 4×4 configurable logic blocks (CLBs) to accommodate the RO bank.

Exploring eco-friendly novel charge transport materials for enhanced performance of tin based perovskite solar cell

This pioneering simulation study explores the potential of perovskite materials, particularly the non-toxic methyl ammonium tin iodide (MASnI3), in solar cell technology. The investigation focuses on eco-friendly, solution-processed compounds—specifically, WO3 and In2S3 as Electron Transport Layers (ETL) and MoO3 and WSe2 as Hole Transport Layer (HTL)—to develop planar n-i-p MASnI3 perovskite solar cell (PSC) devices. WO3 is chosen for its solution processing and high electron mobility, while In2S3 offers n-type properties, superior carrier mobility, non-toxicity, and thermal durability. MoO3 and WSe2 are selected as HTLs for their efficient charge transport capabilities. Utilizing the solar cell capacitance simulator (SCAPS-1D) software, the study systematically evaluates alternative charge-selective materials, considering various parameters such as thickness (0.1 µm to 1.5 µm for absorber and 0.1 µm to 0.35 µm for CTLs), doping concentration (3.2E10 to 3.2E16 for absorber and E16 to E20 for CTLs), defect density, and energy band offset for MASnI3 PSCs. Four distinct n-i-p device structures are optimized, yielding impressive PCE improvements ranging from 14.63 % to 25.34 %, a significant 3 % enhancement compared to initial results. Notably, the WO3/MASnI3/WSe2 configuration exhibits limitations in electrical performance, while the other optimized structures demonstrate substantial efficiency gains. Further analysis investigates the impact of reflecting coatings (10 % to 90 %), varying contact work functions (5.2–5.8 eV), and temperature (300–400 K) on photovoltaic parameters. Critical factors including energy band offset, recombination current profile, and built-in potential, are meticulously examined, laying the groundwork for advanced PSC implementation. The study culminates in the In2S3/MASnI3/MoO3 device configuration, which achieves a peak efficiency of 25.34 %, showcasing superior thermal stability and an enhanced fill factor, thus propelling all-inorganic PSCs towards practical implementation.

Depth-of-field enhancement in light field display based on fusion of voxel information on the depth plane

To improve the performance of 3D light field display(LFD) devices and optimize their display effects, a depth-of-field (DOF) enhancement in LFD based on fusion of voxel information on the depth plane is proposed. In previous research, a calculation method was developed to calculate the voxel size on the depth plane. According to this calculation method, a distribution model of voxel varying with display depth is established. A DOF determination criterion based on voxel distribution from visual perspective is proposed, and its accuracy is validated through subjective experiments involving multiple participants. By fusing the voxels on the depth plane, the phenomenon of voxel overlap is improved, resulting in enhanced definition of 3D images on the depth plane. Under the condition that the structure and parameters of the 3D LFD device are determined, the maximum achievable display depth will be increased significantly. Finally, experimental validation of the method's feasibility is conducted using multiple 3D light field devices for display.

Efficiency optimization of All-Inorganic perovskite solar cell device using NiOx and ZnO as charge transport layers

In this study, we have developed and refined an all-inorganic perovskite solar cell with the structure FTO/ZnO/CsPbBr3/NiOx/Au. This was accomplished by incorporating the inorganic perovskite CsPbBr3 and the inorganic charge transport layers ZnO and NiOx. We employed solvent engineering techniques such as dropping solvents like isopropyl alcohol (IPA) and ethyl acetate (EA) during the spin-coating process, along with optimizing the thickness of the absorber layer and annealing conditions to enhance the power conversion efficiency (PCE). Our evaluation of the impact of the CsPbBr3 absorption layer thickness on PCE revealed that efficiency improved with layer thicknesses up to 280 nm. Moreover, we investigated the influence of post-deposition annealing durations on CsPbBr3, experimenting with times of 0.5hr, 1hr, 2hr, 3hr, and 5hr. The optimal conversion efficiency of 0.91 % was attained with an annealing temperature of 225 °C for 2hr, particularly when the absorption layer thickness was set at 280 nm. These results suggest that the device structure optimization for all-inorganic perovskite quantum dot solar cells can be successfully applied for efficiency optimization.

A Unique Time-Reversal Algorithm-Enabled Flexible Ultrasound Transducer with a Controllable Acoustic Field.

Flexible ultrasonic devices represent a feasible technology for providing timely signal detection and even a non-invasive disease treatment for the human brain. However, the deformation of the devices is always accompanied by a change in the acoustic field, making it hard for accurate focusing. Herein, we report a stable and flexible transducer. This device can generate a high-intensity acoustic signal with a controllable acoustic field even when the device is bent. The key is to use a low-impedance piezoelectric material and an island-bridge device structure, as well as to design a unique time-reversal algorithm to correct the deviation of signals after transcranial propagation. To provide an in-depth study of the acoustic field of flexible devices, we also analyze the effects of mechanical deformation and structural parameters on the corresponding acoustic response.

Gate mesa terminal with drain-field-plated β-Ga2O3 MOSFET with ultra-high power figure of merit

In this article, a novel gate mesa terminal (GMT) device structure incorporating a drain field plate is proposed. This design features mesa terminals with varying bevel angles positioned atop the gate. The objective is to enhance the breakdown voltage (Vbr) and reduce the on-resistance (Ron) of the lateral β-Ga2O3 metal-oxide-semiconductor field-effect transistor (MOSFET). Through the implementation of the GMT structure, the peak electric field within the β-Ga2O3 MOSFET is redirected towards the passivation layer. This effectively mitigates the electric field in the epitaxial layer, thereby increasing Vbr. The optimal values for Vbr, specific on-resistance (Ron,sp) and maximum transconductance (gm) across various GMT structures are 4827 V, 9.9 mΩ·cm2 and 15.32 mS/mm, respectively. These metrics represent a 2.63-fold, 0.88-fold, and 1.25-fold improvement compared to the non-GMT structure. Additionally, when the doping concentration of epitaxial layer is 1 × 1016 cm−3, the GMT achieves an enhanced threshold voltage of +0.26 V. By simulating different bevel angles, field plate parameters, epitaxial layer doping concentrations, and mesa thicknesses, an optimal power figure of merit (PFOM) of 1.914 GW cm−2 is attained. This innovative design introduces a fresh concept for the development of the next generation of high voltage and high-power devices rated above 4 KV.

Electroplating nickel patterns onto polyol-mediated reduced graphene oxide printed textile surfaces

This report explores advancements in multi-step printing/electroplating technique for creating conductive patterns on flexible substrates, which serve as potential structures in wearable electronic devices. The study introduces a novel procedure that employs a sequential process involving polyol screen printing and electroplating, enabling the development of conductive nickel-coated patterns with a conductivity value of about 1123 S/cm on textiles. A significant innovation in this study is the use of a graphene oxide/ethylene glycol (GO/EG) ink, which can be converted into reduced graphene oxide (rGO) through in-situ polyol treatment on the surface of PET fabrics. The effectiveness of this treatment is evidenced by various analytical and microscopic techniques, which confirm the successful printing of conductive rGO patterns onto PET fabric at 220 ˚C. The printed rGO patterns on the fabric surface are then subjected to electroplating as a target substrate and cathode for varying durations, ranging from 5 to 30 minutes. The study thoroughly examines the influence of electroplating time on the microstructures and electrical conductivity of the resulting patterns, with nickel deposition reaching up to 50.8 mg/cm².