Oliva M, Kaganer V, Pudelski M, Meister S, Tahraoui A, Geelhaar L, Brandt O, Auzelle T
Paul-Drude-Institut für Festkörperelektronik, Leibniz-Institut im Forschungsverbund Berlin e.V., Hausvogteiplatz 5-7, D-10117 Berlin, Germany.
Nanotechnology. 2023 Mar 1;34(20). doi: 10.1088/1361-6528/acb949.
We introduce a facile route for the top-down fabrication of ordered arrays of GaN nanowires with aspect ratios exceeding 10 and diameters below 20 nm. Highly uniform thin GaN nanowires are first obtained by lithographic patterning a bilayer Ni/SiNhard mask, followed by a combination of dry and wet etching in KOH. The SiNis found to work as an etch stop during wet etching, which eases reproducibility. Arrays with nanowire diameters down to (33 ± 5) nm can be achieved with a uniformity suitable for photonic applications. Next, a scheme for digital etching is demonstrated to further reduce the nanowire diameter down to 5 nm. However, nanowire breaking or bundling is observed for diameters below ≈20 nm, an effect that is associated to capillary forces acting on the nanowires during sample drying in air. Explicit calculations of the nanowire buckling states under capillary forces indicate that nanowire breaking is favored by the incomplete wetting of water on the substrate surface during drying. The observation of intense nanowire photoluminescence at room-temperature indicates good compatibility of the fabrication route with optoelectronic applications. The process can be principally applied to any GaN/SiNnanostructures and allows regrowth after removal of the SiNmask.
我们介绍了一种自上而下制备氮化镓纳米线有序阵列的简便方法，该阵列的长径比超过10，直径小于20nm。首先通过光刻图案化双层Ni/SiN硬掩膜获得高度均匀的细氮化镓纳米线，随后在KOH中进行干法和湿法蚀刻相结合的工艺。发现SiN在湿法蚀刻过程中起到蚀刻停止层的作用，这有助于提高可重复性。可以实现纳米线直径低至(33±5)nm的阵列，其均匀性适用于光子应用。接下来，展示了一种数字蚀刻方案，可将纳米线直径进一步减小至5nm。然而，对于直径小于约20nm的情况，观察到纳米线断裂或成束，这种效应与在空气中样品干燥过程中作用于纳米线的毛细力有关。毛细力作用下纳米线屈曲状态的明确计算表明，干燥过程中基底表面水的不完全润湿有利于纳米线断裂。室温下纳米线强烈的光致发光表明该制备路线与光电子应用具有良好的兼容性。该工艺原则上可应用于任何GaN/SiN纳米结构，并且在去除SiN掩膜后允许再生长。
