单晶锗表面预制结构辅助纳秒和皮秒激光诱导周期性结构机理研究  

Mechanism of Nanosecond and Picosecond Laser-Induced Periodic Structures Assisted by Prefabricated Structures on Single-Crystal Germanium Surfaces

作　　者：戴晗 韩冰 张静 刘延硕 王仁杰 Dai Han;Han Bing;Zhang Jing;Liu Yanshuo;Wang Renjie(School of Electronic and Optical Engineering,Nanjing University of Science and Technology,Nanjing 210094,Jiangsu,China)

机构地区：[1]南京理工大学电子工程与光电技术学院,江苏南京210094

出　　处：《中国激光》2024年第23期149-167,共19页Chinese Journal of Lasers

基　　金：国家自然科学基金(62275123)。

摘　　要：材料表面预制结构可以调控激光辐照材料表面时的电磁场能量分布,进而影响材料表面激光诱导周期性结构的形成。通过在单晶锗材料表面预制结构,研究了不同预制结构参数、不同脉宽激光热效应以及不同波长入射激光对材料表面电磁场能量分布的影响。结果表明,预制光栅表面熔融区域越大,预制结构槽底电场强度越强,更容易在材料表面产生周期性结构。当预制光栅高度较低时,光栅槽底电场强度会同时受到光栅侧壁和槽底交界处以及光栅侧壁和脊交界处的散射中心的影响,导致光栅凹槽底部的周期性电场分布受到干扰,进而使得光栅凹槽底部不易产生周期性结构。当预制光栅高度较高时,能够进入到槽底的能量较少,光栅槽底同样难以产生周期性结构。此外,在实际应用中0.4~0.6的光栅占空比范围较为合适。对于紫外和红外波段的入射激光,预制结构表面均形成了近波长的周期性电场分布,这导致材料表面出现了近波长的周期性结构。研究结果为预制结构辅助激光诱导半导体表面周期性结构提供了一定参考。Objective Laser-induced periodic surface structure(LIPSS)is a type of periodic micro-nanostructure formed on solid surfaces irradiated by laser light.The generation of periodic micro-nano-structures can improve material surface properties such as optical properties,surface hydrophilicity/hydrophobicity,biomedical properties,and friction properties.Furthermore,this can lead to a wide range of applications in the field of material surface functionalization.Prefabricated structures on material surfaces have been shown to modulate the electromagnetic field energy distribution on material surfaces,which in turn affects the formation of LIPSS on material surfaces.In extant studies,only the influence of prefabricated structures on the electromagnetic field distribution has been discussed.However,there is a significant difference between the thermal effects produced by laser pulses with pulse widths in the order of nanoseconds and picoseconds on the surface of the material.Hence,the aim of this study is to investigate the mechanism of nanosecond-and picosecond laser-induced periodic structure formation assisted by the prefabricated structure on the surface of singlecrystalline germanium.Methods First,the difference in surface temperature changes between picosecond and nanosecond laser irradiation of prefabricated structures is investigated using a two-temperature model.During laser irradiation of the target,the maximum temperature in the center of the groove surface will be higher than the melting point of the single-crystal germanium.This suggests the presence of a molten layer on the surface of the target in the process of laser irradiation.The semiconductor material is instantaneously transformed into a metallic state,which permits the excitation of surface plasma excitations.An interference model of surface plasmon excitations(SPP)is then used to explain the formation mechanism of LIPSS in semiconductor materials.By numerically solving Maxwell equations,the electromagnetic field energy distribution,i.e.,the distribut

关 键 词：激光光学 预制结构 双温方程 激光诱导周期性表面结构 

分 类 号：TN249[电子电信—物理电子学]