1 西安电子科技大学杭州研究院，浙江 杭州 311231
2 西安电子科技大学光电工程学院，陕西 西安 710071
3 上海应用技术大学理学院，上海 201418
在金属铂和非晶硅构成的复合薄膜上，观察到了在斜入射条件下由s偏振激光诱导产生的、具有氧化周期性结构的、远离中轴线且外侧结构倾斜的周期性结构。首先，稳态照射下产生的条纹结构呈叶脉状，既不平行也不垂直于激光偏振方向；其次，动态扫描时产生的结构取向单一且与扫描方向有关；最后，结构周期随着入射角的增大而减小。这几个现象均与通常的激光烧蚀周期性结构不同。这些发现为调控激光诱导自组织提供了更多可能性。
激光诱导周期性表面结构 斜入射 纳米光栅 金属-半导体复合薄膜 激光与光电子学进展
2024, 61(3): 0314001
1 School of Physics and Technology, Wuhan University, Wuhan 430072, Hubei , China
2 State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
3 The Institute of Technological Sciences, Wuhan University, Wuhan 430072, Hubei , China
Gallium nitride (GaN) has widespread applications in the semiconductor industry because of its desirable optoelectronic properties. The fabrication of surface structures on GaN thin films can effectively modify their optical and electrical properties, providing additional degrees of freedom for controlling GaN-based devices. Compared with lithography-based techniques, laser processing is maskless and much more efficient. This paper shows how surface micro-nano structures can be produced on GaN thin films using 355 nm nanosecond laser irradiation. The effects of the laser pulse energy, number of pulses, and polarization direction were studied. It was found that distinct micro-nano structures were formed under different irradiation conditions, and their geometries and elemental compositions were analyzed. The results indicate that different types of surface micro-nano structures can be produced on GaN thin films in a controllable manner using 355 nm nanosecond laser irradiation. The results of our study provide valuable guidance for the surface modification of GaN-based optoelectronic devices.Gallium nitride (GaN) has widespread applications in the semiconductor industry because of its desirable optoelectronic properties. The fabrication of surface structures on GaN thin films can effectively modify their optical and electrical properties, providing additional degrees of freedom for controlling GaN-based devices. Compared with lithography-based techniques, laser processing is maskless and much more efficient. This paper shows how surface micro-nano structures can be produced on GaN thin films using 355 nm nanosecond laser irradiation. The effects of the laser pulse energy, number of pulses, and polarization direction were studied. It was found that distinct micro-nano structures were formed under different irradiation conditions, and their geometries and elemental compositions were analyzed. The results indicate that different types of surface micro-nano structures can be produced on GaN thin films in a controllable manner using 355 nm nanosecond laser irradiation. The results of our study provide valuable guidance for the surface modification of GaN-based optoelectronic devices.
gallium nitride thin films nanosecond laser micro-nano structures laser-induced periodic surface structures 激光与光电子学进展
2023, 60(7): 0714005
Author Affiliations
Abstract
Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generating fuels. These reactions, however, suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst. A large applied electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites, but this comes at the cost of electricity. Here, we report about a ~45% saving in energy to achieve an electrochemical hydrogen generation rate of 3×1016molecules cm–2s–1 (current density: 10 mA/cm2) through localized electric field-induced enhancement in the reagent concentration (LEFIRC) at laser-induced periodic surface structured (LIPSS) electrodes. The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization. When the LIPSS patterned electrodes are used as substrates to support Pt/C and RuO2electrocatalysts, the η10 overpotentials for HER and OER are decreased by 40.4 and 25%, respectively. Moreover, the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes, including alkaline, acidic, neutral, and seawater. Importantly, when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell, it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm2. This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.Electrochemical oxidation/reduction of radicals is a green and environmentally friendly approach to generating fuels. These reactions, however, suffer from sluggish kinetics due to a low local concentration of radicals around the electrocatalyst. A large applied electrode potential can enhance the fuel generation efficiency via enhancing the radical concentration around the electrocatalyst sites, but this comes at the cost of electricity. Here, we report about a ~45% saving in energy to achieve an electrochemical hydrogen generation rate of 3×1016molecules cm–2s–1 (current density: 10 mA/cm2) through localized electric field-induced enhancement in the reagent concentration (LEFIRC) at laser-induced periodic surface structured (LIPSS) electrodes. The finite element model is used to simulate the spatial distribution of the electric field to understand the effects of LIPSS geometric parameters in field localization. When the LIPSS patterned electrodes are used as substrates to support Pt/C and RuO2electrocatalysts, the η10 overpotentials for HER and OER are decreased by 40.4 and 25%, respectively. Moreover, the capability of the LIPSS-patterned electrodes to operate at significantly reduced energy is also demonstrated in a range of electrolytes, including alkaline, acidic, neutral, and seawater. Importantly, when two LIPSS patterned electrodes were assembled as the anode and cathode into a cell, it requires 330 mVs of lower electric potential with enhanced stability over a similar cell made of pristine electrodes to drive a current density of 10 mA/cm2. This work demonstrates a physical and versatile approach of electrode surface patterning to boost electrocatalytic fuel generation performance and can be applied to any metal and semiconductor catalysts for a range of electrochemical reactions.
electric field localization hotspot formation laser-induced periodic surface structures electrochemical fuel generation overall water splitting Opto-Electronic Advances
2022, 5(11): 210105
红外与激光工程
2022, 51(2): 20210911
Author Affiliations
Abstract
1 Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China
2 Han’s Laser Technology Industry Group Co., Ltd., Shenzhen 518126, China
In this work, we used femtosecond laser double-pulse trains to produce laser-induced periodic surface structures (LIPSS) on 304 stainless steel. Surprisingly, a novel type of periodic structure was discovered, which, to the best of our knowledge, is the first in literature. We surmised that the cause for this novel LIPSS was related to the weak energy coupling of subpulses when the intrapulse delay was longer than the thermal relaxation time of stainless steel. Furthermore, we found that the fluence combination and arrival sequence of subpulses in a double-pulse train also influenced LIPSS morphology.
femtosecond laser laser-induced periodic surface structures morphology stainless steel Chinese Optics Letters
2021, 19(12): 123801
1 国防科技大学脉冲功率激光技术国家重点实验室，安徽 合肥 230037
2 国防科技大学先进激光技术安徽省重点实验室，安徽 合肥 230037
激光诱导表面周期性结构（LIPSS）是固体材料的一种普遍特性。材料表面的LIPSS可以改变材料的性质，利用这些特性可以实现许多特殊功能。本文总结近年来关于LIPSS的代表性文章，首先以激光作用下表面能量排布和物质流动方式作为切入点，从理论上解释LIPSS的形成原理；然后阐述薄膜表面与刻蚀材料表面上形成LIPSS的研究工作，以及激光参数对形成LIPSS的影响；最后介绍LIPSS在现代工业中，如制备特殊晶体、超亲水/疏水材料和医学材料等方面的应用情况。本文从以上三个方面对近年来LIPSS相关领域的研究进行了梳理和归纳，对LIPSS相关技术在未来的发展进行展望。
材料 激光损伤 激光诱导表面周期性结构 激光加工 纳米图形制造 激光与光电子学进展
2021, 58(7): 0700007
1 国防科技大学脉冲功率激光技术国家重点实验室, 安徽 合肥 230037
2 国防科技大学先进激光技术安徽省重点实验室, 安徽 合肥 230037
金属铜在中红外波段的发射率极低,所以铜薄膜是一种性能优异且对抗被动式中红外热探测器隐身的材料,而在铜薄膜表面使用激光诱导表面周期性结构(LIPSS)可以显著提高其在中红外波段的发射率。首先使用双温方程模型模拟LIPSS形成过程中材料软化的过程,然后使用波长为1064 nm的偏振脉冲激光在融石英基底上的铜薄膜表面诱导产生周期为波长量级的LIPSS,最后基于实验产生的铜薄膜LIPSS搭建仿真模型并对其在近红外和中红外波段的发射率进行分析。模拟结果表明,铜薄膜LIPSS的产生可以显著提高其在中红外波段的发射率,该方法可以实现铜薄膜对被动式中红外热探测器的隐身。
激光光学 激光损伤 激光诱导表面周期性结构 中红外激光 发射率 反隐身
