Wang Feifei, Jiang Lan, Sun Jingya, Pan Changji, Lian Yiling, Sun Jiaxin, Wang Kai, Wang Qingsong, Wang Jiaxing, Lu Yongfeng
Laser Micro/Nano Fabrication Laboratory, School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China.
Laser Assisted Nano Engineering Laboratory, Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511, United States.
ACS Appl Mater Interfaces. 2021 Feb 17;13(6):7688-7697. doi: 10.1021/acsami.0c19726. Epub 2021 Feb 8.
The third-generation semiconductors are the cornerstone of the power semiconductor leap forward and have attracted much attention because of their excellent properties and wide applications. Meanwhile, femtosecond laser processing as a convenient method further improves the performance of the related devices and expands the application prospect. In this work, an approximate 3 times improvement of the internal quantum efficiency (IQE) and a 5.5 times enhancement of the photoluminescence (PL) intensity were achieved in the GaN film prepared using a one-step femtosecond laser fabrication method. Three types of final micro/nanostructures were found with different femtosecond laser fluences, which could be attributed to the decomposition, melting, bubble nucleation, and phase explosion of GaN. The mechanisms of the microbump structure formation and enhancement of IQE were studied experimentally by the time-resolved reflection pump-probe technique, X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. Simulations for the laser-GaN interaction have also been performed to ascertain the micro/nanostructure formation principle. These results promote the potential applications of femtosecond lasers on GaN and other wide band gap semiconductors, such as UV-light-emitting diodes (LEDs), photodetectors, and random lasers for use in sensing and full-field imaging.
第三代半导体是功率半导体飞跃发展的基石，因其优异的性能和广泛的应用而备受关注。同时，飞秒激光加工作为一种便捷的方法，进一步提升了相关器件的性能并拓展了应用前景。在本工作中，采用一步飞秒激光制备法制备的GaN薄膜实现了内部量子效率（IQE）约3倍的提高以及光致发光（PL）强度5.5倍的增强。发现不同飞秒激光能量密度下会形成三种类型的最终微/纳米结构，这可归因于GaN的分解、熔化、气泡成核和相爆炸。通过时间分辨反射泵浦-探测技术、X射线光电子能谱（XPS）和拉曼光谱对微凸结构的形成机制和IQE的增强进行了实验研究。还对激光与GaN的相互作用进行了模拟，以确定微/纳米结构的形成原理。这些结果推动了飞秒激光在GaN和其他宽带隙半导体上的潜在应用，如用于传感和全场成像的紫外发光二极管（LED）、光电探测器和随机激光器。
