Device Structure Research Articles

A Quasi-Floating Channel-Based SPICE Model for Improving the Modeling Accuracy of SiC MOSFETs With Multiple Device Structures

A Quasi-Floating Channel-Based SPICE Model for Improving the Modeling Accuracy of SiC MOSFETs With Multiple Device Structures

Triple and quadruple metal gate work function engineering to improve the performance of junctionless double surrounding gate In0.53Ga0.47As nanotube MOSFET for the upcoming Sub 3 nm technology node

In line with Moore's Law and the International Roadmap for Devices and Systems (IDRS), shrinking MOSFET dimensions to the 3 nm technology node requires the introduction and thorough investigation of new device structures and advanced materials. The current study focuses on the implementation of Triple Metal (TM) and Quadruple Metal (QM) gate work function engineering techniques on both junctionless (JL) and inversion mode (IM) Double surrounding Gate (DSG) In0.53Ga0.47As nanotube (NT) MOSFET. The objective is to analyze the drain current (ID) characteristics for a gate length of 3 nm using Silvaco ATLAS 3D TCAD. In order to make a fair comparison between JL and IM In0.53Ga0.47As NT, the doping concentration of TM and QM JL In0.53Ga0.47As NT is tuned to achieve two specific objectives. Firstly, the goal is to produce the same ION as IM In0.53Ga0.47As NT. Secondly, the aim is to achieve the same threshold voltage (VTH) as IM In0.53Ga0.47As NT. It was discovered that the IOFF for JL devices is approximately 2.93 times smaller compared to IM devices in the TM situation, while considering matching ION and VTH. The JL devices have an IOFF that is 12.9 times smaller and an IOFF that is 102 times smaller compared to the IM device for the QM situation. This is achieved by matching the ION and VTH values. It achieves a lesser drain-induced barrier lowering (DIBL) of approximately 28.10 mV/V, a virtually perfect subthreshold slope (SS) of roughly 60mV/dec, and a larger current ratio of ION/IOFF, which is approximately 1.42 × 107.

Analysis of air-to-water converter frame using ANSYS simulation

According to projections made by the Indonesian Institute of Sciences (LIPI), by 2040 every region along Java's northern coast—from Banten to Surabaya and Iswara—will be an urban area vulnerable to water scarcity. As a result, more careful consideration is required. Since air is an endless supply, turning it into water is one way to address the clean water shortage. A good design's structure is one of its essential components. This is because the device's structure must sustain both the renewable energy source and the complete system. By utilizing ANSYS Workbench and theoretical calculations to analyze the maximum stress results, the research aims to ascertain whether the machine frame is safe for usage. In this investigation, the ANSYS 2021 R1 software was used to apply the finite element method to ASTM A36 material under vertical loading. The air-to-water converter mechanism is still safe after simulations were run on its shaft and frame. This is demonstrated by the biggest maximum stress on the shaft (6.2194 MPa) from the ANSYS numerical simulation and the largest maximum stress (0.349 MPa) on the frame, both of which are still below the allowable stress. Furthermore, a 0.9694 difference in safety factor was found between theoretical calculations and shaft simulation, and a 0.1573 difference was found for the frame. The safety factor acquired from the shaft was 1.6043, while the safety factor gained from the frame was 1.6073

A Review of Advanced Thermal Interface Materials with Oriented Structures for Electronic Devices

In high-power electronic devices, the rapid accumulation of heat presents significant thermal management challenges that necessitate the development of advanced thermal interface materials (TIMs) to ensure the performance and reliability of electronic devices. TIMs are employed to facilitate an effective and stable heat dissipation pathway between heat-generating components and heat sinks. In recent years, anisotropic one-dimensional and two-dimensional materials, including carbon fibers, graphene, and boron nitride, have been introduced as fillers in polymer-based TIMs due to their high thermal conductivity in specific directions. The orientation of the fillers in the polymer matrix has become an important issue in the development of a new generation of high-performance TIMs. To provide a systematic understanding of this field, this paper mainly discusses recent advances in advanced oriented TIMs with high thermal conductivity (>10 W/(m·K)). For each filler, its preparation strategies and enhancement mechanisms are analyzed separately, with a focus on the construction of oriented structures. Notably, there are few reviews related to carbon fiber TIMs, and this paper details recent research results in this field. Finally, the challenges, prospects, and future development directions of advanced TIMs are summarized in the hope of stimulating future research efforts.

Wafer-scale vertical injection III-nitride deep-ultraviolet light emitters

A ground-breaking roadmap of III-nitride solid-state deep-ultraviolet light emitters is demonstrated to realize the wafer-scale fabrication of devices in vertical injection configuration, from 2 to 4 inches. The epitaxial device structure is stacked on a GaN template instead of conventionally adopted AlN, where the primary concern of the tensile strain for Al-rich AlGaN on GaN is addressed via an innovative decoupling strategy, making the device structure decoupled from the underlying GaN template. Moreover, the strategy provides a protection cushion against the stress mutation during the removal of substrates. As such, large-sized wafers can be obtained without surface cracks, even after the removal of the sapphire substrates by laser lift-off. Wafer-scale fabrication of 280 nm vertical injection deep-ultraviolet light-emitting diodes is eventually demonstrated, where a light output power of 65.2 mW is achieved at a current of 200 mA, largely thanks to the significant improvement of light extraction. This work will definitely speed up the application of III-nitride solid-state deep-ultraviolet light emitters featuring high performance and scalability.

A novel mechanical-laser collaborative intra-row weeding prototype: structural design and optimization, weeding knife simulation and laser weeding experiment.

The competition between intra-row weeds and cultivated vegetables for nutrients is a major contributor for crop yield reduction. Compared with manual weeding, intelligent robots can improve the efficiency of weeding operations. This study proposed a novel mechanical-laser collaborative intra-row weeding device structure. A slider-crank mechanism size optimization algorithm was proposed, and the correctness of the algorithm was verified by ADMAS software. Finally, the crank and link lengths were determined to be 87 mm and 135 mm, respectively. The resistance of triangular weeding knives with different penetration angles and edge angles in the soil was simulated and analyzed using EDEM software. The simulation results show that the triangular weeding knife with a soil penetration angle of 0 ° and an edge angle of 30 ° encountered the least resistance. In addition, weed control experiments with different powers and lasers were conducted using 200 W NIR and 200 W blue lasers. The experimental results show that the time it took for a 50 W blue laser and a 100 W NIR laser to remove small weeds was approximately between 0.3 and 0.4 s, and the time it took for a 50 W blue laser to remove larger weeds was approximately between 0.5 and 0.6 s. The time it took for 75 W and 50 W NIR lasers to remove weeds was more than 1 s. Based on the above research results, a prototype of a mechanical-laser collaborative intra-row weeding device was successfully built. This study provides a new idea for the field of intelligent weeding. The simulation and experimental results can provide a reference for the research and development of mechanical weeding and laser weeding equipment.

Design and Optimization of a Fan-Out Wafer-Level Packaging- Based Integrated Passive Device Structure for FMCW Radar Applications

This paper presents an integrated passive device (IPD) structure based on fan-out wafer-level packaging (FOWLP) for the front end of frequency-modulated continuous wave (FMCW) radar systems, focusing on enhancing the integration efficiency and performance of large passive components like antennas. Additionally, a new metric is introduced to assess this structure’s effect on the average noise figure in FMCW systems. Using this metric as a loss function, we apply the support vector machine (SVM) for electromagnetic simulation and the genetic algorithm (GA) for optimization. The sample fitting variance is 2.42 dB, reducing computation time from 12 min to under 1 millisecond, with the entire optimization completed in less than 100 s. The optimized IPD structure is 0.7 × 0.9 × 0.014 λ03 in size and achieves over 35 dB isolation between the transmitter and receiver. Compared to the IPD model calculated by empirical formulas, the optimized device lowers the average noise figure by 15.2 dB and increases maximum gain by 4.19 dB.

Bulk Heterojunction Perovskite Solar Cells Incorporated with Conjugated Polyfluorenes

Ambipolar transport characteristics of metal halide perovskites (MHPs) enable both hole and electron to be transported simultaneously in perovskite solar cells (PSCs); however, unbalanced charge transport is a fundamental limitation in boosting power conversion efficiency (PCE) of PSCs. Compared to the PSCs with either n–i–p or p–i–n device structures, bulk heterojunction (BHJ) PSCs, inspired by organic photovoltaics, are recognized as superior for balancing charge transport and maximizing interface interactions. This study reports high‐performance BHJ PSCs, where the BHJ composites are composted with the n‐type MHPs mixed with the p‐type conjugated polyfluorenes. In the systematic studies, it is indicated that a small amount of conjugated polyfluorenes component can boost the crystallinity and grain size of the MHP thin film. Moreover, BHJ composite thin films possess boosted charge carrier mobility and a tendency of balanced charge transport and suppress both radiative and non‐radiative charge carrier recombinations. Most importantly, an efficient photoinduced charge transport within the BHJ composite thin film boosts photocurrent. As a result, the PSCs based on the n‐type MHPs:p‐type conjugated polyfluorenes BHJ composite thin film exhibit 23.46% of PCE and boost stability. The results demonstrate a facial method to approach high‐performance PSCs.

Movable surface acoustic wave tweezers: a versatile toolbox for micromanipulation

Surface acoustic wave (SAW) tweezers are a promising multifunctional micromanipulation method that controls microscale targets via patterned acoustic fields. Owing to their device structure and bonding process, most SAW tweezers have limitations in terms of controlling the position and motion of the acoustic traps, as they generate an acoustic field with a fixed region and adjust the manipulation effects via signal modulation. To address this challenge, we propose movable SAW tweezers with a multilayer structure, achieving dynamic control of their wave field and acoustic trap positions; we demonstrate their precise manipulation functions, such as translation, in-plane rotation, out-of-plane rotation, and cluster formation, on a wide spectrum of samples, including particles, bubbles, droplets, cells, and microorganisms. Our method not only improves the degree of freedom and working range of SAW tweezers but also allows for precise and selective manipulation of microtargets via microtools and localized wavefields. Owing to their flexibility, versatility, and biocompatibility, the movable SAW tweezers can be a practical platform for achieving arbitrary manipulation of microscale targets and have the potential to play significant roles in biomedical microrobotics.

Control of coherent phonon dynamics in CoFeB/heavy metal heterojunction structures for future hybrid phononic and spintronic devices

Abstract The heterojunction structure of CoFeB/heavy metal has shown significant potential for spintronics, where both electrons and magnons potentially can serve as information carriers. However, another promising information carrier, coherent phonons, has not been fully explored for hybrid phononic and spintronic devices. In this study, we used time-resolved pump-probe spectroscopy to investigate the dynamic behavior of coherent phonons. We observed variations in reflectivity spectra, corresponding to changes in phonon frequency and relaxation times, with different thicknesses of the heavy metal and CoFeB layers. The experimental results demonstrated a decrease in coherent phonon oscillation frequency as the thickness of the CoFeB and heavy metal layers increased. These findings were further supported by first-principles calculations, which showed that the frequency of the optical modes is suppressed due to interface relaxation between the magnetic and heavy metal layers.

Drain self-blocking ambipolar transistors for complementary circuit applications

The development of complementary metal-oxide-semiconductor field-effect transistor (CMOSFET) based on two-dimensional (2D) materials offers an important opportunity to reduce static power and increase the integration density of integrated circuits. One promising approach to realize these CMOSFETs is to employ ambipolar 2D materials as channel materials with designed device structure to control the carrier transport properties for CMOSFET characteristics. However, these devices always suffer from complex multi-gate electrode structure, and hence face challenges in complicated inter-connection design and excessive voltage source requirement for circuit implementation. Here, we develop a three-terminal CMOSFET using ambipolar 2D material based on the drain electric field-induced carrier injection self-blocking mechanism. The designed drain electrode can effectively suppress carrier injection from the drain to the channel material, while the gate voltage can only regulate carrier injection in the source region. As a result, we can configure the device as either N-field-effect transistors (FET) or P-FET with a high current on/off ratio of over 105 by adjusting the three voltages (gate, source, and drain). Furthermore, we utilize these devices to demonstrate multifunctional wave modulator, low-static-power logic inverter (<5 pW), and combinational logic computing in the form of a compact complementary circuit. Our work would explore an efficient approach for implementing complementary circuits using 2D materials.

Electrical Doping in Sc-III-Nitrides: Toward Multifunctional Devices at the Signal Device Level.

A homogeneous integration of various types of devices using a single material platform is an ideal route toward multifunctional devices at the single-device level for miniaturized, fast, and energy-efficient systems. However, such a single material platform is still missing. Scandium-containing III-nitrides (Sc-III-nitrides) are promising, but their electrical doping properties remain unknown. In this work, the electrical doping in Sc-III-nitrides is investigated and optoelectronic devices using Sc-III-nitrides on silicon (Si) are further demonstrated. The material format of the nanowire is used, with magnesium (Mg) serving as the impurity dopant to control the electrical doping. It is discovered that, by adjusting the Mg doping concentrations, the Sc-III-nitrides can be tuned from n-type to p-type. Device application in light-emitting is further demonstrated using the p-type Sc-III-nitrides as the hole injection layer. The performance comparison between devices using the regrown Sc-containing p-type contact layers and non-Sc-containing p-type contact layers indicates the advantage of Sc incorporation in improving the quality of the regrown p-type layer in a device structure. The electrical doping in Sc-III-nitrides demonstrated in this study represents an important step toward a homogeneous integration of different types of devices using a single material platform.

Enhanced performance of GaN based VCSELs through graded electron-blocking layer design

Electron leakage from the active region to the p-type region restricts the performance of GaN-based Vertical-Cavity Surface-Emitting Lasers (VCSELs). AlGaN EBL can decrease the leakage current, but also raises the hole injection barrier and reduce the hole injection efficiency. Then, it is important to design EBL structures that can enhance both electron blocking and hole injection. In this study, VCSEL devices with three different EBL, basic structure Al0.6Ga0.4N EBL labeled as Device A, newly proposed 16 nm thick Al0.75–0.80Ga0.25–0.20N EBL labeled as Device B, and 18 nm thick Al0.75–0.80Ga0.25–0.20N EBL labeled as Device C, respectively, are designed and analyzed using PICS 3D simulation. Device A represents a basic VCSEL structure, while Device C incorporates a graded electron-blocking layer (EBL) with adjusted thickness. Through simulation results, it is observed that the introduction of a graded EBL in Device C leads to significant performance enhancements compared to the basic structure of Device A. Specifically, the graded EBL effectively reduces band bending and increases the electron barrier height, thereby improving carrier confinement and reducing electron leakage. Additionally, the utilize of a Graded structure in Device C aids in strain relief at the layout between the QB and EBL, resulting in improved electron-blocking capability and potentially enhanced hole transport characteristics. These findings underscore the importance of EBL grading in optimizing the performance of VCSELs, highlighting its potential for advancing the efficiency and functionality of these semiconductor devices. Power of the device C is being improved upto 4.16%, similarly the conduction band barrier height is improved upto 26.6% which is beneficial for better VCSEL performance as it enhances electron confinement in the active region, leading to increased efficiency and reduced carrier leakage and valance band barrier height decreases upto 6.52% and threshold current is decreased upto 4.8% so if valence band barrier height decrease the hole injection efficiency increases and if threshold current decreases the emitting power of the device increase.

Validating the Novel Electron Transport Layer with the Use of Experimentally Studied D18:Y6 Bulk Heterojunction Solar Cell

AbstractOrganic solar cells (OSC) are showing steady efficiency improvement due to the development in the materials synthesis, sophisticated characterization techniques, in‐depth understanding of materials and devices. In the recent years, bulk heterojunction OSC with a non‐fullerene acceptor /polymer acceptor shows significant enhancement in efficiency (≈19%). Efficiency of the polymer acceptor OSCs is much higher than the fullerene derivative‐based acceptors. In this work, OSC simulations are done using D18 donor and Y6 acceptor bulk heterojunction as a photoactive layer. As a first step, validity of the experimental results for ITO/PEDOT:PSS/D18:Y6/PDIN/Ag structure is done. To investigate efficiency, 2,8,15‐trifluoro‐3,9,14‐tris(heptylsulfonyl)diquinoxalino[2,3‐a:2′,3′‐c]phenazine (HATNASO2C7‐Cs) electron transport layer is validated in place of PDIN in the following device structure, ITO/PEDOT:PSS/D18:Y6/HATNASO2C7‐Cs/Ag. Energy level matching of the HATNASO2C7‐Cs is well aligned compared with PDIN at the cathode interface. Device simulation optimization are carried out for various photoactive layer, ETL and HTL condition. Highest efficiency of 20.99% is obtained for ITO/PEDOT:PSS/D18:Y6/HATNASO2C7‐Cs/Ag when the HATNASO2C7‐Cs thickness, bandgap, electron affinity, carrier mobility, and defect density is matched for ≈30 nm, ≈2.8 eV, ≈4.16 eV, ≈2 × 10−3 cm2 V−1 s−1, and 1014 cm−3 respectively. Obtained results are discussed in details and results will be helpful for preliminary understanding of the system.

Innovative design strategies for solar cells: Theoretical examination of linearly graded perovskite solar cell with PTAA as HTL

Over the previous few decades, numerous scientific and theoretical approaches have been employed to increase solar cell efficiency. To improve PV cell efficiency, this study employs grading methodologies and modifies temperature, series resistance, different defect densities, and graded layer thickness. The paper presents a theoretical examination of the linearly graded device structure (Au/PTAA/CsPbBr3-xIx/TiO2/FTO). A linearly graded perovskite layer, responsible for absorbing a wide range of light spectra with different wavelengths, assists in bettering the solar cell's characteristics. In this device, polytriarylamine (PTAA) acts as an HTL, and TiO2 acts as an ETL. SCAPS-1D, a simulation program, is used for our theoretical analysis. The output results obtained from the simulation are as follows: PCE of 20.50 %, JSC of 18.071 mA cm−2, VOC of 1.4531 V, and FF of 78.08 %.

Toward a Procedure for the Template Free Growth of Te Nanowires Across an Insulator by Electrodeposition.

In this work, we present a method for direct, site-selective growth of tellurium nanowires by electrochemical deposition. The Te nanowires were grown laterally between two specially designed nanoband electrodes across a gap, and over a dielectric material, forming a lateral device structure directly. The resulting wires are crystalline and phase pure, as evidenced by Raman spectroscopy, EDS (energy dispersive X-ray spectroscopy), and ADF-STEM (annular dark field scanning transmission electron microscopy). The precise conditions for lateral growth of the nanowires were investigated and the fabrication of an electronic device from the as-deposited material, without the need for any transfer process or further contact fabrication, is demonstrated.

Understanding the Role of Organic Hole Transport Layers on Pinhole Blocking and Performance Improvement in Sb2Se3 Solar Cells

AbstractSb2Se3 is an emerging semiconductor which has shown promise for low‐cost photovoltaic applications. After successive record‐efficiencies using a range of device structures, spiro‐OMeTAD has emerged as the default hole transport material (HTM), however, the function of HTM layers remains poorly understood. Here, thin‐film Sb2Se3 solar cells are fabricated with which three organic HTM layers ‐ namely P3HT, PCDTBT, and spiro‐OMeTAD are investigated. By comparing these against one another, and to a reference device, their role in the device stack are clarified. These organic HTM layers are found to serve a dual purpose, increasing both the average and peak efficiency by simultaneously blocking pinholes and improving the band alignment at the back contact, with marginal differences in performance between the different HTMs. This produced a champion device of 7.44% using P3HT, resulting from an improvement in all performance parameters. A more complex processing route, run‐to‐run variability, and lower overall device performance compared to the other organics challenge the assumption that spiro‐OMeTAD is the optimal HTM for Sb2Se3 devices. A Schottky barrier at the Au‐Sb2Se3 contact despite the deep work function of gold implies Fermi level pinning due to a defective interface, which each of the organic HTMs are equally capable of alleviating.

Understanding the Nonradiative Charge Recombination in Organic Photovoltaics: From Molecule to Device

AbstractOrganic photovoltaics (OPVs) have made significant strides with efficiencies now exceeding 20%, positioning them as potential competitors to inorganic solar technologies. One of the most critical challenges toward this goal is the severe open‐circuit voltage (Voc) loss caused by the nonradiative charge recombination (NRCR). Herein, this review comprehensively summarizes the NRCR mechanisms and suppression techniques of OPVs across various scales from molecule to device. Specifically, the origins of NRCR in a single molecule are first summarized, and molecular design principles toward high photoluminescence quantum yield are reviewed following the Marcus theory. Next, the effect of aggregation on NRCR is reviewed, as well as the molecular and processing strategies to modulate the film packing for NRCR suppression. Furthermore, the progresses in the avoidance of nonradiative loss pathways mediated by charge transfer states and triplet states in donor:acceptor bulk heterojunctions are tracked. Besides, the interfacial optimization and device structure design to maximize the electroluminescent quantum efficiency are presented. Finally, several potential pathways toward curtailing NRCR for high‐performance OPVs are outlined. Therefore, this review shows an insightful perspective to understand and mitigate the NRCR at multi‐scales, and is poised to provide a clear roadmap for the next breakthrough of OPVs.

High performance Au/mix-phase MgZnO/Ga-doped ZnO/In heterojunction solar-blind UV detector with small work voltage

High performance UVC (220 nm–280 nm) detectors with low work voltage is key problem in wide application of UVC optoelectronic device. Here, Au/MgZnO/Ga-doped ZnO/In heterojunction detector is made with both high UVC sensitivity mix-phase MgZnO and high carrier density Ga-doped ZnO conductive layers. The heterostructure detector possess relative high response(0.36A/W)at 254 nm deep UV light without bias voltage. The avalanche breakdown phenomenon within the heterojunction detector, introduced high deep UV response (1390.3 A/W at 3.3 μW/cm2 230 nm) of the Au/MgZnO/Ga-doped ZnO/In heterojunction detector under 5 V bias voltage. The high response of Au/MgZnO/Ga-doped ZnO/In heterojunction detector under low work voltage, is not only much higher than MSM structure MgZnO detector under bias voltage over 25 V, but also higher than reported deep UV detector under small bias voltage. In addition, because of different internal breakdown mechanism, the peak response position of the Au/MgZnO/Ga-doped ZnO/In heterojunction detector is located at shorter wavelength position compared with MSM structure MgZnO detector. Therefore, Au/MgZnO/Ga-doped ZnO/In heterojunction detector is an ideal device structure in low voltage driven detector with relative high response at short wavelength UV light.

Impact of Variable Device Structural Changes on Particle Deposition Distribution in Multi-Rotor UAV

The aim of this study was to investigate the effect of structural changes in variable fertilizer application devices on the distribution of particle deposition in UAVs. With the rapid development of drone technology, particularly in particulate spreading, drones have demonstrated significant potential due to their efficiency and precision. This paper evaluates the impact of different variable adjustment modes of the device on particulate deposition distribution through drone spreading experiments and particulate deposition data analysis. In this study, device structure change is the main variable factor, and flight altitude, flight speed and ambient wind speed are single quantitative factors. Experiments were conducted by varying the structure of the device to test the detailed deposition distribution of the device under group a, b, and c structures. Experimental results indicate that by choosing different variable combinations, the spreading device can achieve various fertilizer deposition states to meet regional needs. Among all 27 variable groups, the fertilizer particle deposition data for group b1b2b3 is relatively uniform, with three-quarters of particulate deposition values being 3 g/m2 and the maximum value being 4 g/m2. However, even with a relatively uniform distribution of fertilizer particles, the coefficient of variation for group b1b2b3 remains high (36.5%), with a range of 4.5% to 41%. Under different group adjustments, the particle distribution shows the smallest variability range in group b1b2b3, with a range of 15.71–26.44% and a variability difference of 10.73%. The particle distribution shows the largest variability range in group a1a2b3, with a range of 0.78–35.06% and a variability difference of 34.28%. These research conclusions provide important guidance for the study and practice of drone spreading systems.