Klaiss Rachael, Ziegler Joshua, Miller David, Zappitelli Kara, Watanabe Kenji, Taniguchi Takashi, Alemán Benjamín
Department of Physics, Material Science Institute, Center for Optical, Molecular, and Quantum Science, University of Oregon, Eugene, Oregon 97403, USA.
Research Center for Functional Materials, National Institute for Materials Science, Tsukuba 305-0044, Japan.
J Chem Phys. 2022 Aug 21;157(7):074703. doi: 10.1063/5.0097581.
Many techniques to fabricate complex nanostructures and quantum emitting defects in low dimensional materials for quantum information technologies rely on the patterning capabilities of focused ion beam (FIB) systems. In particular, the ability to pattern arrays of bright and stable room temperature single-photon emitters (SPEs) in 2D wide-bandgap insulator hexagonal boron nitride (hBN) via high-energy heavy-ion FIB allows for direct placement of SPEs without structured substrates or polymer-reliant lithography steps. However, the process parameters needed to create hBN SPEs with this technique are dependent on the growth method of the material chosen. Moreover, morphological damage induced by high-energy heavy-ion exposure may further influence the successful creation of SPEs. In this work, we perform atomic force microscopy to characterize the surface morphology of hBN regions patterned by Ga FIB to create SPEs at a range of ion doses and find that material swelling, and not milling as expected, is most strongly and positively correlated with the onset of non-zero SPE yields. Furthermore, we simulate vacancy concentration profiles at each of the tested doses and propose a qualitative model to elucidate how Ga FIB patterning creates isolated SPEs that is consistent with observed optical and morphological characteristics and is dependent on the consideration of void nucleation and growth from vacancy clusters. Our results provide novel insight into the formation of hBN SPEs created by high-energy heavy-ion milling that can be leveraged for monolithic hBN photonic devices and could be applied to a wide range of low-dimensional solid-state SPE hosts.
用于量子信息技术的许多在低维材料中制造复杂纳米结构和量子发射缺陷的技术都依赖于聚焦离子束（FIB）系统的图案化能力。特别是，通过高能重离子FIB在二维宽带隙绝缘体六方氮化硼（hBN）中对明亮且稳定的室温单光子发射器（SPE）阵列进行图案化的能力，使得无需结构化衬底或依赖聚合物的光刻步骤就能直接放置SPE。然而，用这种技术创建hBN SPE所需的工艺参数取决于所选材料的生长方法。此外，高能重离子辐照引起的形态损伤可能会进一步影响SPE的成功创建。在这项工作中，我们进行原子力显微镜表征通过Ga FIB图案化的hBN区域的表面形态，以在一系列离子剂量下创建SPE，发现材料膨胀而非预期的铣削与非零SPE产率的开始最强烈且正相关。此外，我们模拟了每个测试剂量下的空位浓度分布，并提出了一个定性模型来阐明Ga FIB图案化如何创建孤立的SPE，该模型与观察到的光学和形态特征一致，并且依赖于对空位团簇中空核形成和生长的考虑。我们的结果为通过高能重离子铣削创建hBN SPE的形成提供了新的见解，可用于单片hBN光子器件，并可应用于广泛的低维固态SPE主体。
