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Analysis and design of a multi-channel constant current LED driver based on DC current bus distributed power system structure
摘要： In this paper, we have extensively investigated the impact of anode recess on the reverse leakage current, forward voltage (VF), and dynamic characteristics of Au-free AlGaN/GaN Schottky barrier diodes with a gated edge termination (GET-SBDs) on 200-mm silicon substrates. By increasing the number of atomic layer etching (ALE) cycles for anode recessing, we have found that: 1) the reverse leakage current is strongly suppressed due to a better electrostatic control for pinching off the channel in the GET region; a median leakage current of ～1 nA/mm and an ION/IOFF ratio higher than 108 have been achieved in GET-SBDs with six ALE cycles; 2) the forward voltage (～1.3 V) is almost independent of the ALE cycles, taking into account its statistical distribution across the wafers; 3) when the remaining AlGaN barrier starts to be very thin (in the case of six ALE cycles), a spread of the ON-resistance, mainly attributed to the GET region, can occur due to the dif?cult control of the remaining AlGaN thickness and surface quality; and 4) the dynamic forward voltage of GET-SBDs shows a mild dependence on the ALE process in pulsed I–V characterization, and a more ALE-dependent dynamic ON-resistance is observed.
关键词： atomic layer etching (ALE),200-mm,leakage,metal–insulator–semiconductor high-electron mobility transistor (MISHEMT),GET-SBD,diode,AlGaN/GaN
更新于2025-09-23 15:21:01
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Ablation of piezoelectric polyvinylidene fluoride with a 193 nm excimer laser
摘要： The unique flexible and piezoelectric properties of polyvinylidene fluoride (PVDF) films would allow for new applications for integrated bioelectronic devices. The use of these films has been precluded by the difficulty in machining them into small, discrete features without damaging the properties of the material. The etching of piezoelectric PVDF by means of a 193 nm excimer laser is explored and characterized. Etch rates are shown for common laser fluence values, along with images of the quality of the cuts to provide the reader with an understanding of the compromise between etch rate and edge roughness. The authors describe a novel method for the etching of piezoelectric, β-phase PVDF. While PVDF is flexible, acoustically matched to biological tissue, and has a wide resonance bandwidth, it is often overlooked as a piezoelectric material for micro-electrical-mechanical-system devices because of the difficulty in fabrication. In this paper, the authors characterize the etch rate and quality while using a 193 nm argon fluoride excimer laser for patterning.
关键词： excimer laser,etching,piezoelectric,ablation,PVDF
更新于2025-09-23 15:21:01
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Improved Leakage and Output Characteristics of Pixelated LED Array for Headlight application
摘要： We investigated the effects of etching conditions on the performance of light-emitting diodes (LEDs) of various sizes aimed at vehicle headlamp applications. Photoluminescence (PL) images showed that after wet etching, the percentage of bad LED arrays significantly increased from 75% to 94%, and the leakage current at ?5 V significantly increased from 1.14 × 10?9 A to 5.02 × 10?6 A. It was shown that plasma etching turned an Ag layer into Ag particles, the size and density of which depended on the treatment time and Ag layer thickness. These Ag particles served as micro-masks during dry etching. Plasma etching produced relatively uniform hillocks of diameters 0.9–1.43 μm and heights 0.85–2.5 μm. Moreover, the PL images showed that dry etching did not degrade the LED arrays. Furthermore, the light output power of the dry-etched LEDs was higher than that of the wet-etched LEDs. For example, the output power levels of the dry-etched LEDs (chip sizes: 240 × 290 μm2, 240 × 490 μm2, and 490 × 1190 μm2) at 100 mA were 20.4%, 15.0%, and 11.2% higher than those of the corresponding wet-etched LEDs, respectively. Moreover, we demonstrated a vehicle headlamp unit consisting of Ag-particle-based plasma-etched LEDs.
关键词： leakage current,vehicle headlamp,light output power,etching,LED
更新于2025-09-23 15:21:01
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Femtosecond Lasera??Etched MXene Microsupercapacitors with Doublea??Side Configuration via Arbitrary Ona?? and Througha??Substrate Connections
摘要： The capacitance of microsupercapacitors (MSCs) can double if both sides of substrates are used to construct MSCs. Nevertheless, achieving electric connections of MSCs through substrates is a challenge due to the difficulty in precisely positioning each MSC couple that has two of the same MSCs units on two sides. In this work, taking advantage of the synchronous etching on both sides of transparent polyethylene terephthalate substrates by femtosecond laser pulses, a double-sided configuration is attained with high precision in the alignment of back-to-back MSC couples and versatile double-side MSCs are realized via arbitrary on- and through-substrate connections of MXene MSC units. The MXene double-side MSC fabricated by the series connection of 12 spiral pattern MXene MSC units with interdigital electrodes of 10 μm width interspace can output a large working voltage of 7.2 V. Additionally, femtosecond laser etching brings the transformation of MXene into titania near-etched edges with a lateral distance less than 1 μm. Such a small laser-affected area has little influence on the capacitive performance, which is one of advantages for femtosecond laser over conventional lasers. This research is valuable for one-step manufacturing of highly integrated MSCs in the field of miniaturized energy storage systems.
关键词： double-sided,microsupercapacitors,femtosecond laser etching,MXene MSCs,MSCs,high integration
更新于2025-09-23 15:21:01
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Fabrication of millimeter-long structures in sapphire using femtosecond infrared laser pulses and selective etching
摘要： This paper analyzes laser and etching parameters to fabricate open and continuous microchannels and stacks of such microchannels in the bulk of crystalline sapphire (??-Al2O3). The structures are produced using a two-step method consisting of laser irradiation and selective etching. Infrared femtosecond laser pulses are focused in the bulk to locally render the crystalline material into amorphous. The amorphous material is, then, selectively etched in hydrofluoric acid. Amorphous sapphire shows a high etching selectivity in comparison to its crystalline state, which makes this material very attractive for a use with this technique. However, some of its properties make the processing challenging, especially during the laser-induced amorphization phase. This paper studies the effect of laser parameters by a step-by-step approach to fabricate long structures (longest dimensions up to millimeters) of different shapes inside the bulk of sapphire. The minimum cross-sectional dimensions of the resulting structures (microchannels) vary from few hundreds of nanometers for the smallest channels to tens of micrometers for the largest stacks of microchannels. The effect of the variation of repetition rate, pulse energy and channel-to-channel distance on the microchannels and stacks of microchannels is studied. SEM micrographs of polished cross-sections are used for performing a quantitative and qualitative analysis of the morphology of the structures after laser irradiation and, subsequently, after selective wet chemical etching.
关键词： Selective etching,Laser processing,Microchannels,Femtosecond laser,Sapphire
更新于2025-09-23 15:21:01
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[IEEE 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Hong Kong, China (2019.8.12-2019.8.15)] 2019 20th International Conference on Electronic Packaging Technology(ICEPT) - Micro-dimple/pillar array molded by a track-etching mold for improving the optical performance of quantum dot film
摘要： Recently, phosphor films have been widely used in display, illumination and other fields. Methods of fabricating structures on phosphor films to enhance their optical properties have attracted great attention in academia and industry. Current methods to fabricate a structured film are mainly by imprinting techniques. However, crystalline silicon or a patterned sapphire substrate are applied to the transfer substrate, which is cumbersome and expensive. This paper describes a track-etching mold, prepared by bombarding a polycarbonate film (PC) with high-speed particles to form phosphor film with microporous structure，which also has a transfer effect. The process is simple and efficient. Simultaneously, the micro-pillar structure PDMS film (MPS-PDMS film) transferred by the PC film has a discrete distribution of micro-pillar structures. Their optical performance was measured and the haze was improved by 12.06% compared with the unstructured PDMS film (US- PDMS film). Subsequently, the micro-dimples structure quantum dots film (MDS-QDs film) was secondarily fabricated using the MPS-PDMS film to have a dimple structure. The red optical power of MDS-QDs film was improved by 7.7% as compared with the unstructured quantum dot film (US-QDs film). Therefore, the structural QD films shows great potential value in luminance and display.
关键词： Track-etching mold,Quantum dots film,Microstructure fabrication,Optical power
更新于2025-09-23 15:21:01
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High-quality nanodisk of InGaN/GaN MQWs fabricated by neutral-beam-etching and GaN regrowth: Towards directional micro-LED in top-down structure
摘要： A nanodisk array of blue InGaN/GaN multiple quantum wells was made using neutral beam etching (NBE) followed by GaN regrowth. The NBE-fabricated nanodisk presented a vertical and highly smooth sidewall surface where the InGaN well layers were easily distinguished even with a scanning electron microscope. A high interface quality without any voids or obvious defects was obtained between the nanodisk and the regrown-GaN layer. The nanodisk after regrowth presented a smaller blueshift of photoluminescence emission energy (12 meV) and a substantially higher and almost constant internal quantum efficiency of ~50% over three orders of magnitude of excitation laser power when compared to the nanodisk before regrowth. This study shows that the process of NBE nanodisk etching followed by GaN regrowth represents a promising step forward in the development of truncated cone-shaped directional micro-LEDs with a buried active region in a top-town structure.
关键词： Regrowth,InGaN/GaN MQWs,Directional micro-LED,Nanodisk,Neutral beam etching
更新于2025-09-23 15:21:01
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Silicon wafer etching by pulsed high-power inductively coupled Ar/CF <sub/>4</sub> plasma with 150 kHz band frequency
摘要： A silicon wafer etching using a burst pulse high-power inductively coupled plasma (ICP) is investigated. A 200 μs wide burst of a 157 kHz power supply is employed to generate ICP with a repetition rate of 50 Hz. A rectangular pulsed voltage synchronized with the burst power supply is applied upto 1 kV at the wafer. Mixed gas of argon (Ar) and tetrafluoromethane (CF4) is supplied into the vacuum chamber. The plasma density and electron temperature are 1019 m?3 and 2.8 eV where the wafer is, respectively. In the case of Ar plasma, the silicon etching rate is 0.01 μm min?1 with 1000 V negative bias. The etching rate increases to 0.23 μm min?1 by adding CF4 into Ar and increases linearly with increasing the bias voltage. The target current and emission intensity of Ar+ and F* are depended on bias voltage from ?300 to ?1000 V. The etching rate sharply increases by increasing CF4 content from 0% to 10%, and it becomes almost constant at 10%. The dependency of emission intensity of F* on CF4 content is similar to the dependency the etching rate.
关键词： Ar/CF4 plasma,high-power inductively coupled plasma,silicon wafer etching,150 kHz band frequency
更新于2025-09-23 15:21:01
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Puffing quaternary FexCoyNi1-x-yP nanoarray via kinetically controlled alkaline etching for robust overall water splitting; ?￠±???è???3??????oè?¨???FexCoyNi1a??xa??yP??????é?μ?????????é?? ???è￡?è§￡?°′??§è??;
摘要： Designing and constructing bifunctional electrocatalysts with high efficiency, high stability and low cost for overall water splitting to produce clean hydrogen fuel is attractive but highly challenging. Here we constructed puffed quaternary FexCoyNi1?x?yP nanoarrays as bifunctional electrodes for robust overall water splitting. The iron was used as the modulator to manipulate the electron density of NiCoP nanoarray, which could increase the positive charges of metal (Ni and Co) and P sites. The resultant electronic structure of FexCoyNi1?x?yP was supposed to balance the adsorption and desorption of H and accelerate the oxygen evolution reaction (OER) kinetics. Moreover, the morphological structure of FexCoyNi1?x?yP was modulated through the kinetically controlled alkaline etching by using the amphoteric features of initial FeCoNi hydroxide nanowires. The resultant puffed structure has rich porosity, cavity and defects, which benefit the exposure of more active sites and the transport of mass/charge. As a result, the cell integrated with the puffed quaternary FexCoyNi1?x?yP nanoarrays as both the cathode and anode only requires the overpotentials of 25 and 230 mV for hydrogen evolution reaction (HER) and OER at the current density of 10 mA cm?2 in alkaline media and a cell voltage of 1.48 V to drive the overall water splitting. Moreover, the puffed FexCoyNi1?x?yP demonstrates remarkable durability for continuous electrolysis even at a large current density of 240 mA cm?2.
关键词： water splitting,puffed nanoarray,electrocatalysis,morphology control,alkaline etching
更新于2025-09-23 15:21:01
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Self-propelled water droplet movement on a laser-etched radial gradient copper surface
摘要： This paper reports the behavior of water droplets on a topography-based, radial gradient on a metallic surface. The radial gradient was designed to concentrate water in the center region through the spontaneous motion and coalescence of individual droplets on the gradient pattern. In this work, parallel microchannels having a fixed width (~25 μm) and depth (100 μm) but variable spacing were used to impart a net surface tension force to the droplet for actuation. The diameter of the radial gradient (i.e. circular test region) was approximately 18.9 mm (or, ~0.75 in.). The surfaces were fabricated using a 355 nm YVO4 laser system and then characterized using droplet injection (5–38 μL) and spray testing techniques. Injected droplets were observed to move spontaneously away from the hydrophobic outer ring region of the circle towards the hydrophilic center as designed by the gradient. Droplet travel distances as large as 4 mm were measured depending on the droplet volume and injection site location. In application, such a design could be useful for promoting droplet coalescence on a surface and subsequently removal by gravity through the formation of sufficiently large droplets from two or more otherwise small droplets.
关键词： Surface tension gradient,Microchannels,Condensation,Heat exchangers,Radial pattern,Laser etching,Water droplet
更新于2025-09-23 15:21:01