Investigation of charge carrier depletion in freestanding nanowires by a multi-probe scanning tunneling microscope
Investigation of charge carrier depletion in freestanding nanowires by a multi-probe scanning tunneling microscope
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DOI：
10.1007/s12274-018-2105-x
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发表时间：
2018-06
期刊：
影响因子：
9.9
通讯作者：
A. Nägelein;M. Steidl;Stefan Korte;B. Voigtländer;W. Prost;P. Kleinschmidt;T. Hannappel
中科院分区：
文献类型：
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作者：
A. Nägelein;M. Steidl;Stefan Korte;B. Voigtländer;W. Prost;P. Kleinschmidt;T. Hannappel
对高空间分辨率的纳米线和纳米线异质接触的电学性质的分析对于任何应用和先进的纳米线器件的开发都是一个挑战。为了进行适当的NW分析，我们建立了一个四点探针仪，它在真空中与最先进的气-液-固制备相结合，能够以高空间分辨率进行无污染的NW表征。利用这种基于超高真空的多尖端扫描隧道显微镜(MT-STM)，我们获得了独立纳米晶的电阻和掺杂分布，以及表面敏感信息。我们的系统内4探针STM方法将低掺杂浓度的检测极限降低到直立NW的耗尽情况，同时提高了空间分辨率，并考虑了可能源于表面变化的径向耗尽区。相应地，无氧化物的GaAsNW{112}面的表面电势低于20 mV，表明NW表面具有很低的表面态密度。
Profiling of the electrical properties of nanowires (NWs) and NW heterocontacts with high spatial resolution is a challenge for any application and advanced NW device development. For appropriate NW analysis, we have established a four-point prober, which is combinedin vacuowith a state-of-the-art vapor-liquid-solid preparation, enabling contamination-free NW characterization with high spatial resolution. With this ultrahigh-vacuum-based multi-tip scanning tunneling microscopy (MT-STM), we obtained the resistance and doping profiles of freestanding NWs, along with surface-sensitive information. Our in-system 4-probe STM approach decreased the detection limit for low dopant concentrations to the depleted case in upright standing NWs, while increasing the spatial resolution and considering radial depletion regions, which may originate from surface changes. Accordingly, the surface potential of oxide-free GaAs NW {112} facets has been estimated to be lower than 20 mV, indicating a NW surface with very low surface state density.