Author Affiliations
Abstract
1 South China University of Technology, School of Physics and Optoelectronics, Guangzhou, China
2 South China University of Technology, State Key Laboratory of Luminescent Materials, Guangzhou, China
3 South China University of Technology, Guangdong Engineering Technology Research and Development Center of Special Optical Fiber Materials and Devices, Guangzhou, China
4 South China University of Technology, Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied Techniques, Guangzhou, China
5 South China Normal University, Research Institute of Future Technology, Guangzhou, China
Laser processing with high-power ultrashort pulses, which promises high precision and efficiency, is an emerging new tool for material structuring. High repetition rate ultrafast laser highlighting with a higher degree of freedom in its burst mode is believed to be able to create micro/nanostructures with even more variety, which is promising for electrochemical applications. We employ a homemade high repetition rate ultrafast fiber laser for structuring metal nickel (Ni) and thus preparing electrocatalysts for hydrogen evolution reaction (HER) for the first time, we believe. Different processing parameters are designed to create three groups of samples with different micro/nanostructures. The various micro/nanostructures not only increase the surface area of the Ni electrode but also regulate local electric field and help discharge hydrogen bubbles, which offer more favorable conditions for HER. All groups of the laser-structured Ni exhibit enhanced electrocatalytic activity for HER in the alkaline solution. Electrochemical measurements demonstrate that the overpotential at 10 mA cm - 2 can be decreased as much as 182 mV compared with the overpotential of the untreated Ni (-457 mV versus RHE).
high repetition rate ultrafast laser burst mode operation nickel electrocatalyst hydrogen evolution reaction Advanced Photonics Nexus
2023, 2(5): 056009
Author Affiliations
Abstract
1 Technical College for the Deaf, Tianjin University of Technology, Tianjin 300384, China
2 School of Science, Tianjin University of Technology, Tianjin 300384, China
Fresnel biprism has been applied to the design of plasmonic meta-lenses recently. In order to promote these applications and understand the physics behind them, in this paper we investigate the focusing effect of Fresnel biprism from the perspective of information optics and geometrical optics. The expression for optical field intensity describing the focusing effect of Fresnel biprism is derived according to the relationship between the impulse response function and the optical field. Then the formula of the focal length is achieved. Furthermore, the Fresnel biprism focusing experiment is performed. Specially, the optical field intensity distribution is measured and the corresponding intensity along the axis is obtained. The results show that the focusing effect depends on the base angle, refractive index and base length of the biprism. There exists axial resonance effect in the axial intensity. The experimental results are in accordance with the theoretical results. These results could be valuable to the applications of Fresnel biprism in designing large depth of focus plasmonic meta-lenses.
光电子快报（英文版）
2023, 19(3): 151
基于横向双扩散金属氧化物半导体(LDMOS)的可控硅结构(LDMOS_SCR)因其较强的单位面积电流处理能力和出色的高压特性，通常用于高压下的静电防护。通过将原本浮空的漏极N+分割为对称的P+、N+和P+结构，提出了一种基于LDMOS_SCR的双向防护器件。该器件具有低触发和高维持电压。通过降低形成在栅极区域底部的寄生双极晶体管的发射极注入效率，减少了SCR固有的正反馈增益。基于TCAD进行仿真，实验结果表明，与传统的LDMOS_DDSCR相比，新型器件的触发电压从69.6 V降到48.5 V，维持电压从14.9 V提高到17 V，证明了提出的结构与传统LDMOS_DDSCR器件相比具有出色的抗闩锁能力
静电放电 维持电压 横向双扩散金属氧化物半导体 可控硅结构 TCAD仿真 ESD holding voltage LDMOS silicon controlled rectifier TCAD simulation
传统低压触发可控硅(LVTSCR)维持电压过低, 应用于片上ESD防护时存在闩锁风险。文章提出了一种嵌入分流路径的LVTSCR。基于0.18 μm CMOS工艺, 使用Sentaurus-TCAD软件模拟人体模型, 对器件准静态特性进行了分析。结果表明, 新型器件在保持触发电压、ESD防护性良好的情况下, 有效提高了维持电压。对关键尺寸D6进行优化, 该器件的维持电压提高到5.5 V以上, 器件可安全应用于5 V电压电路, 避免了闩锁效应。
静电放电 可控硅 维持电压 闩锁 分流 ESD LVTSCR holding voltage latch-up shunt path
1 郑州大学 集成电路可靠性设计与静电防护实验室, 郑州 450000
2 西安理工大学 自动化与信息工程学院, 西安 710000
3 长鑫存储技术有限公司, 合肥 230000
提出了一种用于降低触发电压的两级防护SCR(TSPSCR)。在传统LVTSCR中植入P-ESD层, 增设额外的二极管。因为P-ESD层的掺杂浓度较高, 该器件能更早发生雪崩击穿而触发第一级泄流路径, 从而开启第二级泄流路径。Sentaurus TCAD仿真结果表明, 该器件的触发电压从传统器件的10.59 V降低至4.12 V, 维持电压为1.25 V, 1 V直流电压下漏电流仅为7.85 nA。优化后的TSPSCR适用于先进1 V工作电压的电路中。
两级防护 触发电压 漏电流 ESD ESD SCR SCR two-stage-protection trigger voltage leakage current
横向双扩散MOSFET(LDMOS)由于其高击穿电压特性而被认为是适合在高压中应用的防止静电放电(ESD)现象的保护器件。在传统结构中, LDMOS的鲁棒性相对较差, 这是器件自身固有的不均匀导通特性和Kirk效应导致的。可将可控硅整流器(SCR)嵌入到LDMOS结构(即NPN_LDMOS)中。然而, SCR固有的正反馈效应会导致其维持电压较低, 增加了被闩锁的风险。提出了一种基于NPN_LDMOS的新型器件, 可以实现更高的维持电压以及较小的占用面积。基于TCAD进行仿真, 实验结果表明, 在不增加芯片面积的情况下, 器件的维持电压从7.3 V增加到22.5 V。这证明了提出的结构具有出色的抗闩锁能力。
静电放电 维持电压 横向双扩散金属氧化物半导体 闩锁效应 TCAD仿真 ESD holding voltage LDMOS latch-up effect TCAD simulation
