Department of Electrical and Computer Engineering, University of Nebraska-Lincoln, NE 68588-0511, USA.
Nanoscale. 2017 Jul 6;9(26):8997-9008. doi: 10.1039/c7nr01712j.
It is known that defects strongly influence the properties of two-dimensional (2D) materials. The controlled creation and removal of defects can be utilized to tailor the optical and electronic responses of these 2D materials for optoelectronic and nanoelectronic applications. In this study, we developed an efficient approach to reversibly control the defect states in mechanically exfoliated graphene and molybdenum disulfide (MoS) monolayers. The defects were created by aluminium oxide (AlO) plasmas and removed by moderate thermal annealing at up to 300 °C. We employed Raman and photoluminescence (PL) as well as electrical characterization to monitor the variation of the defect level in graphene and MoS. For graphene, Raman spectra indicate that the AlO plasma induced sp-type defects with a controlled concentration, which have been substantially removed after thermal annealing. A similar trend was also observed in monolayer MoS, as revealed by the defect-related emission peak (X) in the PL spectra. We further showed that the defects induced by the AlO plasma in both 2D materials can be restored to any intended level via annealing under well-controlled conditions. Our work presents a new route to the functional design of the optical and electronic properties of graphene and MoS-based devices through defect engineering.
已知缺陷强烈影响二维（2D）材料的性质。可以通过控制缺陷的产生和去除来调整这些 2D 材料的光学和电子响应，以满足光电和纳米电子应用的需求。在这项研究中，我们开发了一种高效的方法来可逆地控制机械剥离的石墨烯和二硫化钼（MoS）单层中的缺陷态。通过氧化铝（AlO）等离子体产生缺陷，并在高达 300°C 的温度下进行适度的热退火来去除缺陷。我们采用拉曼和光致发光（PL）以及电特性来监测石墨烯和 MoS 中缺陷水平的变化。对于石墨烯，拉曼光谱表明，AlO 等离子体诱导了具有可控浓度的 sp 型缺陷，这些缺陷在热退火后已基本去除。在 MoS 的单层中也观察到了类似的趋势，这可以通过 PL 光谱中与缺陷相关的发射峰（X）来证明。我们进一步表明，通过在 AlO 等离子体中产生的缺陷可以通过在受控条件下退火来恢复到任何预期的水平。我们的工作为通过缺陷工程来设计石墨烯和 MoS 基器件的光学和电子性质提供了一种新途径。
