Nanofabrication Using High Frequency Laser Ablation and Laser Maskless Lithography

我建议的研究计划将集中在超短激光材料加工及其在微/纳米制造中的应用。纳米结构材料由于其特殊的光学、生物学和机械性能而迅速引起研究人员的兴趣，这些性能不同于块状材料。在纳米结构中观察到的结构纳米流动性和纳米柔性为光伏器件开发独特的光学特性以及不同分子和电池之间的物理化学相互作用机制提供了机会。 我的研究将在纳米技术领域开创一个重要的新方向。纳秒激光烧蚀加工传统上用于微米和纳米尺度的材料去除;然而，由于其效率低，它很少用于纳米材料合成。基于激光的纳米材料合成通常采用高功率连续激光器和纳秒激光器，并且需要催化剂和受控环境。然而，在兆赫激光脉冲频率下，连续脉冲之间的延迟时间与成核的临界时间相当，这使得在不添加催化剂的情况下在环境条件下形成纳米结构成为可能。 我以前对激光微/纳米加工的研究为使用超短激光器进行微/纳米材料加工奠定了基础。这些研究发现了与高脉冲频率激光-物质相互作用相关的新现象，从而可以从不同类型的材料中产生各种形式的薄膜，亚微米图案和纳米结构。这一发现有望带来高频激光材料加工的范式转变，并将为工程师提供亚微米图案化和薄膜生成的重要新工具。该技术还开辟了生成纳米结构的可能性，例如纳米纤维结构、纳米复合材料和纳米合金，这些都难以通过任何其他手段合成。我的研究表明，通过控制激光特性，可以在硅衬底上生成非晶化或氧化硅薄膜，然后可以用于太阳能电池制造，也可以用于微机电（MEMS）系统和生物医学设备制造。 我提出的工作将通过展示一种新的纳米混合材料和基于薄膜的无掩模光刻，生物医学和光伏器件制造基板来实现飞跃。此外，我将重点展示分析方法-基于光热理论和有限元模拟-可以描述激光-物质相互作用，激光等离子体和羽流产生，以及激光参数可以影响所创建的微/纳米颗粒的大小和质量的方法。

My proposed research program will focus on ultrashort-laser materials processing and its applications in micro/nano fabrication. Nanostructured materials are rapidly gaining interest among researchers due to their exceptional optical, biological, and mechanical properties, which differ from those of bulk-form materials. The structural nano-mobility and nano-flexibility observed in nanostructures provide opportunities to develop unique optical properties for photovoltaic devices, as well as physico-chemical interactive mechanisms between different molecules and cells. My research will initiate a major new direction in the field of nanotechnology. Nanosecond-laser ablative machining has traditionally been used for material removal at micro- and nanoscales; due to its low efficiency, however, it is rarely used for nanomaterial synthesis. Laser-based nanomaterial synthesis normally employs high-powered continuous lasers and nanosecond lasers, and requires catalysts and a controlled environment. At megahertz laser-pulse frequency, however, the delay time between successive pulses is comparable to the critical time of nucleation, which enables the formation of nanostructures in ambient conditions without the addition of a catalyst. My previous research on laser micro/nano fabrication has contributed to establishing the groundwork for micro/nano material processing using ultrashort lasers. These investigations led to the discovery of a new phenomenon associated with high pulse-frequency laser-matter interaction, whereby thin-film, sub-micro patterns and nanostructures of various forms can be generated from different types of materials. This discovery is poised to bring about a paradigm shift in high frequency-laser material processing and will provide engineers with an important new tool for sub-micro patterning, and thin-film generation. This technique also opens up the possibility of generating nanostructures, such as nanofibrous structures, nanocomposites, and nanoalloys, which are difficult to synthesize by any other means. My research has demonstrated that by controlling laser properties, it is possible to generate a thin-film of amorphorized or oxidized silicon on top of a silicon substrate, which can then be used for solar-cell fabrication and also for microelectromechanical (MEMS) systems and biomedical devices fabrication. My proposed work will take a leap forward by demonstrating a new nano-hybrid material and thin-film-based substrate for maskless photolithography, biomedical and photovoltaic devices fabrication. In addition, I will focus on demonstrating analytical methods - based on photo-thermal theory and finite element simulation - that can describe laser-matter interaction, laser plasma and plume generation, and the method by which laser parameters can affect the size and quality of micro/nano particles that are created.