High Performance Laser Scribing of Advanced Thin Film Materials

薄膜材料在电子、光源、可再生能源、传感器、机械系统等方面有着广泛的应用。随着新型薄膜结构的出现，对高性能激光刻划技术的需求不断增加，这种技术能够产生窄（10微米）、直壁切割，并且表面损伤很小。本研究旨在从根本上解决这一问题，研究激光双脉冲辐照下薄膜刻划激光与物质的相互作用机制。该项目的基础研究将产生科学知识，以促进高性能激光划线技术的发展，这些技术可以在许多先进技术领域找到应用，包括太阳能电池和智能窗户玻璃的划线，柔性电子元件的图案，微机电系统和发光二极管的微加工等。例如，在太阳能工业中，近年来薄膜太阳能光伏发电取得了巨大进展，特别是钙钛矿太阳能电池的功率转换效率超过了20%。这项研究可以加速薄膜太阳能技术的采用，并有助于实现一个没有空气污染、危险废物和负面环境影响的清洁能源未来。除了潜在的工业和社会效益外，该项目还将开发引人入胜的教育材料和活动，以培养不同群体的本科生和研究生，并为K-12学生和公众提供教育。首席研究员将利用新的激光微加工基础设施，让来自代表性不足群体的学生参与该项目。该研究将验证飞秒-皮秒双脉冲辐照将通过多光子吸收和雪崩电离产生均匀的临界电子数密度，并使具有高表面完整性的窄薄膜刻划器成为可能。研究目标是确定脉冲能量和时间延迟的参数窗口，并确定双脉冲辐照方案下激光与物质的相互作用机制。实验和数值模拟相结合的方法将用于验证该方法，并深入了解在飞秒-皮秒脉冲序列照射下薄膜结构中的电子动力学和烧蚀机制。基本的技术方法是建立一个数值模型来预测自由载流子密度和由此产生的烧蚀形状，而基于模型的方法将用于设计和进行薄膜刻划实验。这项研究将通过推进对激光物质与先进薄膜材料相互作用的基本理解，为科学界做出贡献。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Thin film materials have broad application in electronics, light source, renewable energy, sensors, mechanical systems, etc. With the emergence of new thin film structures there is increasing demand for high performance laser scribing techniques capable of producing narrow ( 10 micron), straight walled cuts with little imparted surface damage. The research aims to address this challenge at the fundamental level by studying the laser-matter interaction mechanisms under a new laser double pulse irradiation strategy for thin film scribing. The basic research from this project will generate scientific knowledge to enable the development of high performance laser scribing techniques that can find application in numerous advanced technology areas including scribing of solar cells and smart window glass, patterning of flexible electronics, micromachining of microelectromechanical systems and light emitting diodes, etc. In the solar industry, for example, recent years have seen tremendous progress in thin film solar photovoltaics, especially perovskite solar cells exceeding 20 percent power conversion efficiency. The research could accelerate the adoption of thin film solar technology and contribute to a clean energy future free of air pollution, hazardous waste, and negative environmental impact. Besides potential industrial and societal benefits, engaging educational materials and activities derived from the project will be developed to train a diverse group of undergraduate and graduate students, and to educate both K-12 students and the public. The principle investigator will take advantage of the new laser micromachining infrastructure to involve students from underrepresented groups in the project. The research will verify that a femtosecond-picosecond double pulse irradiation will create a uniform critical electron number density through multiphoton absorption and avalanche ionization and enable a narrow thin film scribe with high surface integrity. The research objective is to identify the parameter window for pulse energy and time delay, and determine the laser-matter interaction mechanisms under this double pulse irradiation scheme. A combined experimental and numerical modeling approach will be used to verify the approach and to gain a deep understanding of electron dynamics and ablation mechanisms in a thin film structure when irradiated by a femtosecond-picosecond pulse train. The basic technical approach is to develop a numerical model to predict the free carrier density and the resulting ablation shape, while a model-based approach will be used to design and conduct thin film scribing experiments. This research will contribute to the scientific community by advancing the fundamental understanding of laser-matter interaction with advanced thin film materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.