Kavli Institute of Nanoscience, Delft University of Technology , Lorentzweg 1, 2628 CJ Delft, The Netherlands.
Department of Applied Physics, TU Eindhoven , Den Dolech 2, 5612 AZ Eindhoven, The Netherlands.
Nano Lett. 2017 Apr 12;17(4):2259-2264. doi: 10.1021/acs.nanolett.6b04891. Epub 2017 Feb 28.
The ability of core-shell nanowires to overcome existing limitations of heterostructures is one of the key ingredients for the design of next generation devices. This requires a detailed understanding of the mechanism for strain relaxation in these systems in order to eliminate strain-induced defect formation and thus to boost important electronic properties such as carrier mobility. Here we demonstrate how the hole mobility of [110]-oriented Ge-Si core-shell nanowires can be substantially enhanced thanks to the realization of large band offset and coherent strain in the system, reaching values as high as 4200 cm/(Vs) at 4 K and 1600 cm/(Vs) at room temperature for high hole densities of 10 cm. We present a direct correlation of (i) mobility, (ii) crystal direction, (iii) diameter, and (iv) coherent strain, all of which are extracted in our work for individual nanowires. Our results imply [110]-oriented Ge-Si core-shell nanowires as a promising candidate for future electronic and quantum transport devices.
核壳纳米线克服异质结构现有局限性的能力是设计下一代器件的关键因素之一。这需要深入了解这些系统中应变弛豫的机制，以消除应变诱导的缺陷形成，从而提高载流子迁移率等重要的电子特性。在这里，我们展示了如何通过在该系统中实现大的能带偏移和相干应变，大幅提高[110]取向 Ge-Si 核壳纳米线的空穴迁移率，在 4 K 时达到高达 4200 cm/（Vs），在室温下对于高空穴密度 10^16 cm^-3，达到 1600 cm/（Vs）。我们提出了迁移率、晶体方向、直径和相干应变之间的直接相关性，所有这些都是我们在工作中针对单个纳米线提取的。我们的结果表明，[110]取向 Ge-Si 核壳纳米线是未来电子和量子输运器件的有前途的候选材料。
