摘要
纳米材料具备小尺寸和大比表面积的特点,在能源器件、集成电路和生物医学等领域中具有众多独特的优势。目前,研究人员通过固相、液相或者气相沉积等方法实现了各类纳米材料的高质量制备,但这些方法主要聚焦于纳米材料的生长过程,通常需要后续多步工艺配合才能实现微纳器件的制备。因此,对纳米材料的直接图案化制备将有效提高器件的集成度,并将充分发挥纳米材料的尺寸优势。尽管已有部分方法能够实现原位免转移的纳米材料图案化制备,如紫外光刻、电子束光刻、溶液直接成型以及连续/长脉冲激光选择性诱导生长等,但仍难以满足纳米材料的图案定制化、精密化以及在热敏、柔性和曲面衬底上原位异质集成的需求。飞秒激光作为一种具有高峰值功率的“冷加工”手段,在实现纳米材料的原位图案化生长方面具有独特的优势。回顾了现有的纳米材料的原位图案化制备方法,总结了这些方法存在的问题,并重点介绍了飞秒激光诱导纳米材料的图案化生长方面的研究进展,包括金属、金属氧化物、金属硫化物以及碳基纳米材料的图案化生长及其应用。最后探讨了飞秒激光诱导纳米材料图案化生长需要解决的问题以及其在未来微纳功能器件制造中的应用前景和发展潜力。
Significance Nanomaterials with small features and large surface-to-volume ratios have drawn tremendous research attention in various fields including energy devices,microelectronics,and biomedicine.By far,researchers have realized high-quality fabrication of various nanomaterials through solid-phase,liquid-phase,or vapor-phase method.However,the fabrication of nanomaterial-based functional devices usually requires subsequent material transfer and assembly processes.Therefore,to effectively realize the integration of nanomaterials and make full use of their unique properties,the transfer-free growth of patterned nanomaterials is very important.Although methods have been developed to realize the in-situtransfer-free patterned growth of nanomaterials,such as ultraviolet lithography,electron beam lithography,solution-based direct-patterning technique,and continuous wave/long pulsed laser selective induction,it is still difficult to meet the demands of customized patterning,precise processing,and in-situ heterogeneous integration of nanomaterials on thermal-sensitive,flexible,and curved substrates.The UV lithography and electron beam lithography techniques are cumbersome,time-consuming,and usually need a vacuum chamber.Besides,they are difficult to apply to curved substrates.The solution-based direct-patterning technique requires the subsequent high-temperature annealing process,which is difficult to apply to thermal sensitive substrates.The CW/long pulsed laser selective induction method is difficult to achieve high precision and highly localized growth due to the diffraction limit effect and the sizeable heat-affected zone.Due to these drawbacks of the existing methods,researchers have attempted to use a femtosecond laser to realize the direct patterned growth of nanomaterials.As a “cold processing” method with a high peak power,the femtosecond laser direct writing is a promising tool to achieve the direct patterned growth of nanomaterials.The focus of a femtosecond laser can be regarded as a flexible,controllable and highly localized micro-reactor,which can realize the fixed-point growth of nanomaterials.At the same time,according to the pre-designed patterns,the laser focus position can be changed by the galvanometer,displacement stage or other equipment to realize the transferfree patterned growth of nanomaterials.Compared with the current commonly used CW or long pulsed laser,a femtosecond laser has unique advantages in the transfer-free patterned growth of nanomaterials.First,due to its small heat-affected zone,it can be applied to thermal-sensitive substrates.Second,the ultra-high energy density of a femtosecond laser can induce nonlinear multi-photon absorption of precursors,which can realize the direct absorption of laser energy.Therefore,the femtosecond laser induced direct patterned growth of nanomaterials can be applied to transparent substrates without heat-absorbing layers.Third,the threshold effect of nonlinear absorption and the small heat-affected zone of a femtosecond laser can realize the high-precision growth of nanomaterials.Thus,the femtosecond laser induced patterned growth of nanomaterials has unique advantages and excellent prospects.Progress In this review,we first summarize the commonly used patterned synthesis methods of nanomaterials and their problems,including UV/electron beam lithography,solution-based direct patterning,and CW/long pulsed laser induced growth of nanomaterials.Then we discuss the unique advantages of the femtosecond laser-induced patterned growth method of nanomaterials,including high precision,highly localized growth,and high processing compatibility with thermal sensitive and transparent substrates.Next,the recent progress of the femtosecond laser induced direct patterned growth of nanomaterials and their applications are reviewed,including metal,metal oxide,metal sulfide,and carbon-based nanomaterials.For metal materials,researchers realized silver and gold patterned micro-nano structures with high conductivity[Fig.4(a)],which are comparable to the bulk materials.To grow more high-precision products,researchers realized silver nanostructures with a minimum feature size of only 180nm with the help of surfactant[Fig.4(c)].Researchers realized a stable 3D connection between two pairs of metal electrodes.As for metal oxides,researchers realized the patterned SnO_(2) structure with the line width of about 150nm through femtosecond laser direct writing (FLDW)and subsequent annealing process (Fig.5).Our group realized the patterned growth of ZnO and SnO_(2) through femtosecond laser direct writing without subsequent annealing(Figs.8 and 9).The minimum linewidth is about 800nm.For metal sulfide,our group realized the patterned growth of MoS2 through femtosecond laser induced photochemical reaction (Fig.10).For carbon-based nanomaterials,researchers realized the patterned growth of graphene through femtosecond laser induced reduction of graphene oxide[Fig.12(b)].Researchers realized the patterned growth of graphene through FLDW of cosputtering Ni/C films.The sheet resistivity of the products is about 205Ω/sq[Fig.12(a)].Conclusion and Prospect Compared with traditional methods,the femtosecond laser induced direct patterned growth technique has many unique advantages.Due to the extremely small heat-affected zone and the nonlinear multi-photon absorption effect of a femtosecond laser,the femtosecond laser induced direct patterned growth technique can realize the high precision,highly localized patterned growth of nanomaterials and has high processing compatibility with thermal sensitive and transparent substrates.Besides,the femtosecond laser induced direct patterned growth technique does not need a vacuum chamber or the high-temperature annealing process.Thus,it has drawn tremendous research attention around the world.Although the femtosecond laser induced direct patterned growth technique has made some progresses,several problems remain to be resolved.First,the products need to be expanded and the precursor needs to be optimized to reduce the required laser energy and take full use of the advantages of a femtosecond laser.Second,in term of the processing system,a Gaussian beam can be converted into a flat-top beam by beam shaping,thereby improving the uniformity of the products.The processing efficiency can be improved by employing scanning devices with high scanning frequency or adopting parallel processing strategies including multi-point scanning,line scanning,and plane projection.Finally,the application of this method needs to be explored,such as MEMS,soft electronics,metasurfaces,energy and catalytic devices.
作者
薛松岩
胡化策
徐一诺
王莹琛
龙婧
焦玢璋
刘耘呈
范旭浩
高辉
邓磊敏
熊伟
Xue Songyan;Hu Huace;Xu Yinuo;Wang Yingchen;Long Jing;Jiao Binzhang;Liu Yuncheng;Fan Xuhao;Gao Hui;Deng Leimin;Xiong Wei(Wuhan National Laboratory for Optoelectronics,School of Optical and Electronic Imformation,Huazhong Universityy of Science and Techuology,Whan 430074,Hubei,China;Optics Valley Laboratory Wuhan 430074,Hubei,China)
出处
《中国激光》
EI
CAS
CSCD
北大核心
2022年第12期105-127,共23页
Chinese Journal of Lasers
基金
国家重点研发计划(2017YFB1104300)
国家自然科学基金面上项目(61774067)。
关键词
纳米材料
飞秒激光
图案化生长
非线性多光子吸收
热影响区
laser technique
nanomaterials
femtosecond laser
patterned growth
nonlinear multiphoton absorption
heat-affected zone
