Enhanced Device Performance Research Articles

Hybrid Integrated Silicon Photonics Based on Nanomaterials

Integrated photonic platforms have rapidly emerged as highly promising and extensively investigated systems for advancing classical and quantum information technologies, since their ability to seamlessly integrate photonic components within the telecommunication band with existing silicon-based industrial processes offers significant advantages. However, despite this integration facilitating the development of novel devices, fostering fast and reliable communication protocols and the manipulation of quantum information, traditional integrated silicon photonics faces inherent physical limitations that necessitate a challenging trade-off between device efficiency and spatial footprint. To address this issue, researchers are focusing on the integration of nanoscale materials into photonic platforms, offering a novel approach to enhance device performance while reducing spatial requirements. These developments are of paramount importance in both classical and quantum information technologies, potentially revolutionizing the industry. In this review, we explore the latest endeavors in hybrid photonic platforms leveraging the combination of integrated silicon photonic platforms and nanoscale materials, allowing for the unlocking of increased device efficiency and compact form factors. Finally, we provide insights into future developments and the evolving landscape of hybrid integrated photonic nanomaterial platforms.

TCAD Simulation of Novel Recess Gate Common Drain Dual Channel AlGaN/GaN HEMT for Small Signal Performance

In this paper, DC and RF characteristics of Recess Gate Common Drain Dual Channel (CDDC) AlGaN/GaN HEMT have been investigated. The performance of the device in terms of the various figures of merits including gate-source capacitance, drain current, transconductance, and channel conductance has been studied for different recess depths. The threshold voltage is found to decrease by shifting right with increasing recess depth, even though with deeper recess, transconductance increases. It has also been observed that the device operates in enhancement mode with a minimum gate recess depth of 15 nm or more. With increasing recess depth, the drain current starts decreasing due to an increase in channel resistance. Use of recess technology with Al graded barrier layer enhances the performance in terms of gm, ft, and fmax which are 0.003 S, 23, and 46 GHz, respectively, but utilizing gate recess technology alone in CDDC HEMT further enhances device performance and the maximum gm, ft, and fmax are 0.0442 S, 28.43, and 59.21 GHz. The CDDC HEMT retain its advantage for specific applications including PA, LNA, and RF switch with optimized gate recess and graded barrier layer parameters.

Cryogenic Electron-Beam Writing for Perovskite Metasurface.

Halide perovskites (HPs) metasurfaces have recently attracted significant interest due to their potential to not only further enhance device performance but also reveal the unprecedented functionalities and novel photophysical properties of HPs. However, nanopatterning on HPs is critically challenging as they are readily destructed by the organic solvents in the standard lithographic processes. Here, we present a novel, subtle, and fully nondestructive HPs metasurface fabrication strategy based on cryogenic electron-beam writing. This technique allows for high-precision patterning and in situ imaging of HPs with excellent compatibility. As a proof-of-concept, broadband absorption enhanced metasurfaces were realized by patterning nanopillar arrays on CH3NH3PbI3 film, which results in photodetectors with approximately 14-times improvement on responsivity and excellent stability. Our findings highlight the great feasibility of cryogenic electron-beam writing for producing perovskite metasurface and unlocking the unprecedented photoelectronic properties of HPs.

Enhancement of device performance in β-Ga2O3 Schottky barrier diodes with tetramethylammonium hydroxide treatment

Schottky barrier diodes were fabricated on tetramethylammonium hydroxide (TMAH)-treated β-Ga2O3 surfaces with Ni/Au as Schottky metal contacts. TMAH wet surface treatment efficiently reduced the roughness of the β-Ga2O3 surface. An X-ray photoelectron emission analysis of the TMAH-treated β-Ga2O3 surface chemical binding features indicates the effective removal of unwanted surface oxides and contaminants formed unintentionally by chemisorption during exposure to ambient conditions. The TMAH-treated Au/Ni/β-Ga2O3 Schottky diode displayed improved rectification behavior with an increment of barrier height by 0.30 eV compared to the untreated diode. The breakdown voltages (Vbr) for the untreated and TMAH-treated Au/Ni/β-Ga2O3 Schottky barrier diode are 298 and 358 V, respectively. The decrease in the turn-on resistance (Ron) in the Au/Ni/β-Ga2O3 Schottky barrier diode by TMAH treatment can be ascribed to the improved surface morphology. The improved electrical behavior of the Au/Ni/β-Ga2O3 Schottky barrier diode formed on the TMAH-treated β-Ga2O3 surface can be accredited to the oxygen vacancies reduction, that deceased the carrier concentration in the β-Ga2O3 epilayer and to the improved the surface morphology. These results demonstrate the effectiveness of TMAH wet surface treatment on β-Ga2O3 and its potential as a simple method for fabricating β-Ga2O3-based devices with improved performance.

Study on the Fabrication and Acoustic Properties of Near-Stoichiometric Lithium Tantalate Crystal Surface Acoustic Wave Filters

Near-stoichiometric lithium tantalate (NSLT) wafers with different Li contents were prepared by vapour transfer equilibrium (VTE) method and fabricated into surface acoustic wave filters. The temperature coefficient of frequency, insertion loss, and bandwidth of the surface acoustic wave filters were tested using a special chip test bench and a network analyzer. The results show that the temperature coefficient of frequency shows a trend of first decreasing and then increasing with the increase in Li content, and the temperature stability of the surface acoustic wave filters is best when the Li content is 49.75%. It is also found that the surface acoustic wave filter fabricated from NSLT wafers has 21.18% lower temperature coefficient of frequency, 7.3% lower insertion loss, and 2.8% lower bandwidth than those fabricated from congruent lithium tantalate wafers. Therefore, NSLT crystals are more suitable for applications in acoustic devices, providing a new idea for performance enhancement of 5G communication devices.

Enhancing the Permeate Flux Improvement of Direct Contact Membrane Distillation Modules with Inserted S-Ribs Carbon-Fiber Filaments.

Three widths of manufacturing S-ribs carbon-fiber filaments acting as turbulence promoters were implemented into the flow channel of direct contact membrane distillation (DCMD) modules to augment the permeate flux improvement in the present study. Attempts to reduce the disadvantageous temperature polarization effect were made by inserting S-ribs turbulence promoters in improving pure water productivity, in which both heat- and mass-transfer boundary layers were diminished due to creating vortices in the flow pattern and increasing turbulence intensity. The temperature polarization coefficient ttemp was studied and found to enhance device performance (less thermal resistance) under inserting various S-ribs carbon-fiber thicknesses and operating both cocurrent- and countercurrent-flow patterns. The permeate fluxes in the DCMD modules with inserted S-ribs carbon-fiber turbulence promoters were investigated theoretically by developing the mathematical modeling equations and were conducted experimentally with various design and operating parameters. The theoretical predictions and experimental results exhibited a great potential to considerably achieve permeate flux enhancement in the new design of the DCMD system. The DCMD module with inserted S-ribs carbon-fiber turbulence promoters in the flow channel could provide a relative permeate flux enhancement up to 37.77% under countercurrent-flow operations in comparisons with the module of using the empty channel. An economic consideration on both permeate flux enhancement and power consumption increment for the module with inserted S-ribs carbon-fiber filaments was also delineated.

Functionalized MXene ink enables environmentally stable printed electronics

Establishing dependable, cost-effective electrical connections is vital for enhancing device performance and shrinking electronic circuits. MXenes, combining excellent electrical conductivity, high breakdown voltage, solution processability, and two-dimensional morphology, are promising candidates for contacts in microelectronics. However, their hydrophilic surfaces, which enable spontaneous environmental degradation and poor dispersion stability in organic solvents, have restricted certain electronic applications. Herein, electrohydrodynamic printing technique is used to fabricate fully solution-processed thin-film transistors with alkylated 3,4-dihydroxy-L-phenylalanine functionalized Ti3C2Tx (AD-MXene) as source, drain, and gate electrodes. The AD-MXene has excellent dispersion stability in ethanol, which is required for electrohydrodynamic printing, and maintains high electrical conductivity. It outperformed conventional vacuum-deposited Au and Al electrodes, providing thin-film transistors with good environmental stability due to its hydrophobicity. Further, thin-film transistors are integrated into logic gates and one-transistor-one-memory cells. This work, unveiling the ligand-functionalized MXenes’ potential in printed electrical contacts, promotes environmentally robust MXene-based electronics (MXetronics).

Exploring the optimal design space of transparent perovskite solar cells for four-terminal tandem applications through Pareto front optimization

Machine learning algorithms can enhance the design and experimental processing of solar cells, resulting in increased conversion efficiency. In this study, we introduce a novel machine learning-based methodology for optimizing the Pareto front of four-terminal (4T) perovskite-copper indium selenide (CIS) tandem solar cells (TSCs). By training a neural network using the Bayesian regularization-backpropagation algorithm via Hammersley sampling, we achieve high prediction accuracy when testing with unseen data through random sampling. This surrogate model not only reduces computational costs but also potentially enhances device performance, increasing from 29.4% to 30.4% while simultaneously reducing material costs for fabrication by 50%. Comparing experimentally fabricated cells with the predicted optimal cells, the latter show a thinner front contact electrode, charge-carrier transport layer, and back contact electrode. Highly efficient perovskite cells identified from the Pareto front have a perovskite layer thickness ranging from 420 to 580 nm. Further analysis reveals the front contact electrode needs to be thin, while the back contact electrode can have a thickness ranging from 100 to 145 nm and still achieve high efficiency. The charge-carrier transport layers play a crucial role in minimizing interface recombination and ensuring unidirectional current flow. The optimal design space suggests thinner electron and hole transport layer thicknesses of 7 nm, down from 23 to 10 nm, respectively. It indicates a balanced charge-carrier extraction is crucial for an optimized perovskite cell. Overall, the presented methodology and optimized design parameters have the potential to enhance the performance of 4T perovskite/CIS TSC while reducing material fabrication costs.

Fluorinated Polyimide Tunneling Layer for Efficient and Stable Perovskite Photovoltaics

AbstractDespite the remarkable progress of perovskite solar cells (PSCs), challenges remain in terms of finding effective and viable strategies to enhance their long‐term stability while maintaining high efficiency. In this study, a new insulating and hydrophobic fluorinated polyimide (FPI: 6FDA‐6FAPB) was used as the interface layer between the perovskite layer and the hole transport layer (HTL) in PSCs. The functional groups of FPI play a pivotal role in passivating interface defects within the device. Due to its high work function, FPI demonstrates field‐effect passivation (FEP) capabilities as an interface layer, effectively mitigating non‐radiative recombination at the interface. Notably, the FPI insulating interface layer does not impede carrier transmission at the interface, which is attributed to the presence of hole tunneling effects. The optimized PSCs achieve an outstanding power conversion efficiency (PCE) of 24.61 % and demonstrate excellent stability, showcasing the efficacy of FPI in enhancing device performance and reliability.

Fluorinated Polyimide Tunneling Layer for Efficient and Stable Perovskite Photovoltaics.

Despite the remarkable progress of perovskite solar cells (PSCs), challenges remain in terms of finding effective and viable strategies to enhance their long-term stability while maintaining high efficiency. In this study, a new insulating and hydrophobic fluorinated polyimide (FPI: 6FDA-6FAPB) was used as the interface layer between the perovskite layer and the hole transport layer (HTL) in PSCs. The functional groups of FPI play a pivotal role in passivating interface defects within the device. Due to its high work function, FPI demonstrates field-effect passivation (FEP) capabilities as an interface layer, effectively mitigating non-radiative recombination at the interface. Notably, the FPI insulating interface layer does not impede carrier transmission at the interface, which is attributed to the presence of hole tunneling effects. The optimized PSCs achieve an outstanding power conversion efficiency (PCE) of 24.61 % and demonstrate excellent stability, showcasing the efficacy of FPI in enhancing device performance and reliability.

Numerical optimization of interface engineering parameters for a highly efficient HTL-free perovskite solar cell

Decarbonizing the world’s energy system has set the stage in favor of renewable energy alternatives such as the more reliable, abundant, inexhaustible, and sustainable solar energy. However, the photovoltaic technology faces significant stability, longevity, and scalability challenges. These difficulties can be overcome by judicious optimization of interfacial engineering of the solar cell architecture that will decrease the cost of fabrication and enhance the solar cell performance and durability. Herein, a comprehensive analysis of a novel high-performance hole transport layer-free (HTL-free) perovskite solar cell (PSC) of the configuration, ITO/PC61BM/CH3NH3SnI3/Pt, was investigated by device simulation while optimizing electron transport materials, metal back contacts, front contact materials, and buffer layers. The focus is on enhancing device performance by introducing various types of buffer layers, such as cadmium sulphide (CdS) in the proposed solar cell model. By fine-tuning the ETL layers and manipulating perovskite acceptor and donor densities, better device performance was achieved. Furthermore, the Mott-Schottky capacitance analysis yielded critical insights into the interface properties and dynamics of charge carriers within the solar cell structure. Optimizing back contacts also play a critical role in charge extraction and reduced recombination losses. Leveraging a sophisticated simulation platform, SCAPS-1D, the study assesses how design strategies impact photovoltaic electrical outcomes such as open-circuit voltage (Voc), power conversion efficiency (PCE), short-circuit current density (Jsc), and Fill factor (FF). The proposed HTL-free device posted remarkable results – PCE of 38.11 %, Jsc of 35.32 mAcm−2, FF of 88.67 %, and Voc of 1.2168 V. Accordingly, this work inspires the promising prospects of HTL-free PSCs in achieving robust solar harvesting capabilities while streamlining device affordability. Therefore, the proposed device architecture stimulates the journey towards affordable and high-performance scalable solar cell modules.

Highly Efficient Pure‐Red Quasi‐2D Perovskite Light‐Emitting Diodes Enabled by Propylammonium Chloride Passivator

AbstractPerovskite light‐emitting diodes (PeLEDs) based on quasi‐2D perovskites have attracted great attention in the past few years. Although significant achievements are made in device performance, fabrication of high‐efficiency PeLEDs with pure‐red (620–635 nm) light emission remains a significant challenge, which inhibits their practical application for full‐color displays. Herein, a series of efficient red PeLEDs at 625 nm are realized by employing volatile alkylammonium chlorides (propylammonium chloride) passivators. The interaction of PbI2 with propylamine (PA)…H+Cl− in the precursor solution effectively passivates the defects, leading to reduced non‐radiative recombination and enhanced device performance. By optimizing the amount of PACl, an external quantum efficiency (EQE) of 16.1% and a maximum brightness of 1701 cd m−2 are achieved, among the best‐performing quasi‐2D I‐based PeLEDs with emissions ranging from 620 to 635 nm. This work provides a new route to improve the stability and efficiency of pure‐red PeLEDs.

A numerical investigation of the two-dimensional magnetohydrodynamic water-based hybrid nanofluid flow composed of Fe3O4 and Au nanoparticles over a heated surface

Abstract In this research article, the viscous, steady, and incompressible two-dimensional hybrid nanofluid flow composed of Fe3O4 and Au nanoparticles on an extending sheet has been presented. An inclined magnetic field impact is used for evaluating the impacts of various factors in that case. Furthermore, the influences of porosity, Brownian motion, thermophoresis, thermal and space-dependent heat sources, and thermal radiation factors are also used in this work. The numerical analysis is done by using the bvp4c technique. Validation of the present results confirms that the present analysis is valid. The outcomes show that the higher magnetic factor reduces velocity distribution while increasing the frictional force at the surface due to Lorentz forces which oppose the fluid flow. The friction force at the sheet’s surface is higher when the sheet stretches as compared to the case when the sheet shrinks. Increase in the magnetic factor increases the skin friction of sheet’s surface which consequently increases the rate of thermal transmission at the surface along with thermal distribution. The higher values of thermal radiation and thermal-dependent heat source increase the thermal transportation rate of sheet’s surface. Insights from this investigation can improve electronics cooling systems, vital for devices prone to overheating. Optimizing heat transfer with magnetohydrodynamic water-based hybrid nanofluids containing Fe3O4 and Au nanoparticles ensures efficient heat dissipation, enhancing device performance and longevity.

Improvement of Ga2O3 vertical Schottky barrier diode by constructing NiO/Ga2O3 heterojunction

The high critical electric field strength of Ga2O3 enables higher operating voltages and reduced switching losses in power electronic devices. Suitable Schottky metals and epitaxial films are essential for further enhancing device performance. In this work, the fabrication of vertical Ga2O3 barrier diodes with three different barrier metals was carried out on an n–-Ga2O3 homogeneous epitaxial film deposited on an n+-β-Ga2O3 substrate by metal−organic chemical vapor deposition, excluding the use of edge terminals. The ideal factor, barrier height, specific on-resistance, and breakdown voltage characteristics of all devices were investigated at room temperature. In addition, the vertical Ga2O3 barrier diodes achieve a higher breakdown voltage and exhibit a reverse leakage as low as 4.82 ×10−8 A/cm2 by constructing a NiO/Ga2O3 heterojunction. Therefore, Ga2O3 power detailed investigations into Schottky barrier metal and NiO/Ga2O3 heterojunction of Ga2O3 homogeneous epitaxial films are of great research potential in high-efficiency, high-power, and high-reliability applications.

Unraveling Bulk versus Surface Passivation Effects in Highly Efficient p–i–n Perovskite Solar Cells Using Thiophene‐Based Cations

Defect passivation is nowadays considered a must‐have route for high‐efficiency perovskite solar cells. However, a general rule that correlates the choice of passivating agents with performance enhancements is still missing. Herein, two different thiophene salts that are used as passivating agents are compared, namely thiophene methylammonium chloride and thiophene ethylammonium chloride (TEACl), which are used for the passivation of bulk and surface defects in triple‐cation‐based metal halide perovskites. First, it is observed that the surface passivation method leads to better device performances reaching a power conversion efficiency of 23.56%, with reduced voltage losses and increased fill factor when compared with the reference. Second, it is demonstrated that the chemical structure of the cation dictates its capability either in passivating bulk defects effectively or to form a superficial two‐dimensional/three‐dimensional heterostructure, which happens only for the TEACl case. The chemical composition and the cation dimension are responsible for device performance enhancement as observed by a joint spectroscopic and density functional theory simulations study, providing rational guidelines for further smart device design.

Recent Advances of VO2 in Sensors and Actuators.

Vanadium dioxide (VO2) stands out for its versatility in numerous applications, thanks to its unique reversible insulator-to-metal phase transition. This transition can be initiated by various stimuli, leading to significant alterations in the material's characteristics, including its resistivity and optical properties. As the interest in the material is growing year by year, the purpose of this review is to explore the trends and current state of progress on some of the applications proposed for VO2 in the field of sensors and actuators using literature review methods. Some key applications identified are resistive sensors such as strain, temperature, light, gas concentration, and thermal fluid flow sensors for microfluidics and mechanical microactuators. Several critical challenges have been recognized in the field, including the expanded investigation of VO2-based applications across multiple domains, exploring various methods to enhance device performance such as modifying the phase transition temperature, advancing the fabrication techniques for VO2 structures, and developing innovative modelling approaches. Current research in the field shows a variety of different sensors, actuators, and material combinations, leading to different sensor and actuator performance input ranges and output sensitivities.

Atomic-scale simulation of ultrasonic vibration-assisted polishing process for graphene/GaN-layered composites

In the realm of semiconductor materials, the integration of graphene (Gr) and gallium nitride (GaN) has emerged as a promising avenue for enhancing device performance. In this study, a Gr/GaN layered nanocomposite was constructed using molecular dynamics simulation and the LAMMPS code. Diamond abrasive was pressed into the composite at a speed of 50 m/s at 300 K, followed by ultrasonic vibration-assisted polishing on the (0001) plane along the [01‾10] direction. By rigorously exploring various factors such as number of Gr layers, vibration amplitudes, vibration frequencies and grinding speeds, the study elucidates the intricate mechanisms governing material removal and subsurface damage. Key findings reveal optimal processing conditions, including three layers of Gr, an amplitude of 5 Å, a vibration frequency of 80 GHz and a grinding speed of 100 m/s, which result in enhanced material removal rates and improved surface quality. Additionally, the insertion of Gr layers within the GaN matrix demonstrates a remarkable reduction in friction and wear rates, highlighting the potential for enhancing device reliability and performance. This comprehensive investigation not only advances our understanding of ultrasonic vibration-assisted grinding processes but also underscores the transformative impact of Gr/GaN composites in semiconductor device fabrication.

Smart fin with automatic evaporation and regeneration for thermal management of high heat flux electronics

The high temperature of modern electronic devices poses great challenges to the safety and reliability of applications. Reasonable and effective control of device operating temperature for enhancing device performance and promoting the development of the electronics industry has a positive effect. Here, an innovative and efficient passive cooling technology is proposed to reduce the device temperature using polymerized metal fin and smart hydrogel to form smart fin. The smart fin carries away the waste heat generated by the device through evaporation and regeneration is accomplished by capturing water molecules from the environment. The smart fin is demonstrated to low down the temperature of a heater with heat flux of 2900 W/m2 by 48.3 °C and restores to its initial state after 160 min. At a threshold temperature of 60 °C, it promoted the maximum usage power by 49.4%. The evaporation and regeneration capacity of the smart fin can be controlled by ambient temperature, relative humidity, and smart hydrogel thickness. Specifically, high temperatures promote water evaporation and absorption, high humidity suppresses evaporation but favors absorption, and excessive thickness impedes water transport. This thermal management strategy with simple structure, low-cost, and easy-preparation is expected to become a universal technology in the electronics industry.

From wide to ultrawide-bandgap semiconductors for high power and high frequency electronic devices

Abstract Wide and ultrawide-bandgap (U/WBG) materials have garnered significant attention within the semiconductor device community due to their potential to enhance device performance through their substantial bandgap properties. These exceptional material characteristics can enable more robust and efficient devices, particularly in scenarios involving high power, high frequency, and extreme environmental conditions. Despite the promising outlook, the physics of UWBG materials remains inadequately understood, leading to a notable gap between theoretical predictions and experimental device behavior. To address this knowledge gap and pinpoint areas where further research can have the most significant impact, this review provides an overview of the progress and limitations in U/WBG materials. The review commences by discussing Gallium Nitride, a more mature WBG material that serves as a foundation for establishing fundamental concepts and addressing associated challenges. Subsequently, the focus shifts to the examination of various UWBG materials, including AlGaN/AlN, Diamond, and Ga2O3. For each of these materials, the review delves into their unique properties, growth methods, and current state-of-the-art devices, with a primary emphasis on their applications in power and radio-frequency electronics.

Morphologically engineered multi-component organic solar cells with stratified donor distribution and alloyed acceptors for enhanced efficiency and stability

The strategy of integrating multiple components within the bulk-heterojunction layer of organic photovoltaics (OPVs) has proven effective in enhancing device performance and demonstrates broad potential applications. Nonetheless, achieving precise control over the morphology in such a multifaceted system presents a significant challenge. In this work, we introduce an innovative sequential casting technique to fabricate highly efficient quaternary OPVs with a meticulously tailored morphology featuring layers of stratified donor distribution and composite alloyed acceptors. The layered configuration of D18/PTQ10, with distinct crystalline domains, establishes a dedicated hole-transport pathway, while the alloyed BTP-eC9:Y6-O acceptors are evenly dispersed across the layered D18/PTQ10 donor phase. This carefully crafted morphology presents a gradient and interpenetrated donor/acceptor phase separation at an ideal length scale, which facilitates exciton dissociation, minimizes energetic disorder, and mitigates recombination. As a result, a power conversion efficiency close to 19% with excellent operational stability (extrapolated T80 = 818 h) was achieved. This work offers valuable insights into the morphological engineering of multicomponent OPVs for improved performance.