Formation of Ge–GeS core–shell nanostructures via solid-state sulfurization of Ge nanowires
Formation of Ge–GeS core–shell nanostructures via solid-state sulfurization of Ge nanowires
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DOI：
10.1039/c8ce00221e
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发表时间：
2018-04
期刊：
影响因子：
3.1
通讯作者：
C. Keiser;P. Sutter;E. Sutter
中科院分区：
文献类型：
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作者：
C. Keiser;P. Sutter;E. Sutter
锗纳米线（NW）具有用于各种应用的吸引人的性质，包括微电子学和光电子学、存储器件、太阳能转换和能量存储等。对于涉及暴露于空气的应用，天然氧化物的化学稳定性差和电子表面钝化一直是长期关注的问题。终止富硫的表面层已成为一个有前途的战略钝化平面锗表面。在这里，我们讨论了固态硫化锗纳米线在硫蒸气在近环境压力和在不同的温度下的实验。结合透射电子显微镜成像和化学映射建立Ge NW在高温下与S的气相反应期间保持完整，并显示在Ge NW表面上形成具有T依赖的形态和厚度的富硫壳。这种核-壳纳米线的系综的光致发光由在1.85eV处的强发射主导，与GeS的发光一致。个别纳米线的阴极发光光谱确定，这种发光起源于薄的硫化形成的纳米线的GeS壳。我们的工作建立了直接硫化作为一种可行的方法，形成稳定的，宽带隙的表面终端锗纳米线。
Germanium nanowires (NWs) have attractive properties for a variety of applications, including micro- and optoelectronics, memory devices, solar energy conversion, and energy storage, among others. For applications that involve exposure to air, the poor chemical stability and electronic surface passivation of native oxides have remained a long-standing concern. Termination by sulfur-rich surface layers has emerged as a promising strategy for passivation of planar Ge surfaces. Here we discuss experiments on solid-state sulfurization of Ge nanowires in sulfur vapor at near-ambient pressures and at different temperatures. Combined transmission electron microscopy imaging and chemical mapping establishes that Ge NWs remain intact during vapor-phase reaction with S at elevated temperatures, and show the formation of sulfur-rich shells with T-dependent morphology and thickness on the Ge NW surface. Photoluminescence of ensembles of such core–shell nanowires is dominated by strong emission at ∼1.85 eV, consistent with luminescence of GeS. Cathodoluminescence spectroscopy on individual NWs establishes that this luminescence originates in thin GeS shells formed by sulfurization of the NWs. Our work establishes direct sulfurization as a viable approach for forming stable, wide-bandgap surface terminations on Ge NWs.