Fabrication of microchannels in single-crystal GaN by wet-chemical-assisted femtosecond-laser ablation
Fabrication of microchannels in single-crystal GaN by wet-chemical-assisted femtosecond-laser ablation
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DOI：
10.1016/j.apsusc.2009.04.159
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发表时间：
2009-09
影响因子：
6.7
通讯作者：
S. Nakashima;K. Sugioka;K. Midorikawa
中科院分区：
文献类型：
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作者：
S. Nakashima;K. Sugioka;K. Midorikawa
本文研究了利用飞秒激光制备宽频带隙半导体氮化镓（GaN）的微纳米工艺。利用湿化学辅助fs激光烧蚀技术，将激光束聚焦在盐酸（HCl）溶液中的单晶GaN衬底上，成功地形成了纳米级的激光坑。这可以有效地去除消融过程中化学反应产生的消融碎片，从而实现高质量的消融。然而，一种两步处理方法，包括在空气中使用fs激光束照射，然后进行湿法蚀刻，由于残留的碎片而扭曲了陨石坑的形状。湿化学辅助fs激光烧蚀的阈值比空气中fs激光烧蚀的阈值更低，这有利于提高制造分辨率，因为它减少了热效应。我们利用孔径为0.73的高数值孔径物镜制作了直径为510nm的弹坑。此外，我们还利用光纤激光在HCl溶液中直接写入，在GaN中形成了三维空心微通道。
We investigated micro- and nano-fabrication of wide band-gap semiconductor gallium nitride (GaN) using a femtosecond (fs) laser. Nanoscale craters were successfully formed by wet-chemical-assisted fs-laser ablation, in which the laser beam is focused onto a single-crystal GaN substrate in a hydrochloric acid (HCl) solution. This allows efficient removal of ablation debris produced by chemical reactions during ablation, resulting in high-quality ablation. However, a two-step processing method involving irradiation by a fs-laser beam in air followed by wet etching, distorts the shape of the crater because of residual debris. The threshold fluence for wet-chemical-assisted fs-laser ablation is lower than that for fs-laser ablation in air, which is advantageous for improving fabrication resolution since it reduces thermal effects. We have fabricated craters as small as 510nm by using a high numerical aperture (NA) objective lens with an NA of 0.73. Furthermore, we have formed three-dimensional hollow microchannels in GaN by fs-laser direct-writing in HCl solution.