Department of Materials, University of Oxford , Parks Road, Oxford OX1 3PH, United Kingdom.
ACS Nano. 2016 Jan 26;10(1):1093-100. doi: 10.1021/acsnano.5b06408. Epub 2015 Dec 4.
We study how grain boundaries (GB) in chemical vapor deposition (CVD) grown monolayer WS2 influence the electroluminescence (EL) behavior in lateral source-drain devices under bias. Real time imaging of the WS2 EL shows arcing between the electrodes when probing across a GB, which then localizes at the GB region as it erodes under high bias conditions. In contrast, single crystal WS2 domains showed no signs of arcing or localized EL. Analysis of the eroded GB region shows the formation of micro- and nanoribbons across the monolayer WS2 domains. Comparison of the EL spectrum with the photoluminescence spectrum from the monolayer WS2 shows close agreement, indicating the EL emission comes from direct band gap excitonic recombination. These results provide important insights into EL devices that utilize CVD grown monolayer transition metal dichalcogenides when GBs are present in the active device region.
我们研究了化学气相沉积（CVD）生长的单层 WS2 中的晶界（GB）如何影响偏置下横向源漏器件中的电致发光（EL）行为。WS2 的 EL 实时成像显示，在探测 GB 时，电极之间会出现电弧，当在高偏置条件下侵蚀时，电弧会集中在 GB 区域。相比之下，单晶 WS2 域没有电弧或局部 EL 的迹象。对侵蚀的 GB 区域的分析表明，在单层 WS2 域上形成了微带和纳米带。EL 光谱与单层 WS2 的光致发光光谱的比较表明，两者非常吻合，表明 EL 发射来自直接带隙激子复合。这些结果为在有源器件区域存在 GB 的情况下利用 CVD 生长的单层过渡金属二卤化物的 EL 器件提供了重要的见解。
