posted on 2016-01-26, 00:00authored byYoumin Rong, Yuewen Sheng, Mercè Pacios, Xiaochen Wang, Zhengyu He, Harish Bhaskaran, Jamie H. Warner
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.