Band Engineering of Dirac Materials for Device Applications

本研究提出开发一种可扩展的、复杂性较低的方法来调制二维（2D）狄拉克材料（包括石墨烯、硅烯和过渡金属二硫族化物）的能带结构，用于电子和能源技术。用金属纳米结构或聚合物分子对二维狄拉克材料进行图案修饰将被探索作为一种有效的手段来调节二维狄拉克系统中选定区域的能带隙，同时保持其固有的电学和光学性质。在加拿大光源上使用x射线吸收和发射光谱对带工程材料的详细电子结构进行表征，以揭示通过表面改性打开二维材料带隙的机制。这些带工程二维狄拉克材料最终将用于生产高性能晶体管和太阳能电池器件。为了实现优化的器件性能，将对器件工作参数（例如晶体管器件的载流子迁移率和通/关比以及太阳能电池器件的能量转换效率）与表面覆盖和装饰材料类型进行定量分析。

This research proposes to develop a scalable method with less complexity to modulate the band structure of two dimensional (2D) Dirac materials including graphene, silicene, and transition metal dichalcogenides for applications in electronics and energy technologies. Patterned decoration of 2D Dirac materials with metallic nanostructures or polymer molecules will be explored as an effective mean to tune the energy band gap in selected areas of 2D Dirac systems while preserving their intrinsic electrical and optical properties. The characterization of detailed electronic structure for the band-engineered materials will be conducted using X-ray absorption and emission spectroscopy at the Canadian Light Source to shed light on the mechanism behind the opening of band gap in 2D materials by surface modification. These band-engineered 2D Dirac materials will ultimately be used to produce high performance transistor and solar cell devices. The quantitative analysis of the device operation parameters (for example, carrier mobility and on/off ration for transistor devices and energy conversion efficiency for solar cell devices) with respect to the surface coverage and type of decorating materials will be conducted in order to achieve the optimized device performance. The following objectives will be pursued as main directions toward semiconductor Dirac electronics: a) investigation of the effect of metallic nanostructure formation (and followed by oxidation if necessary) and organic material decoration on the band structure of group-IV 2D Dirac materials (graphene and silicene) and transition metal dichalcogenide (MoS2), b) design and fabrication of electronic and photovoltaic device architectures using the selected-area band-engineered materials, and c) optimization of the current-voltage (I-V) characteristics of devices. This research program is of great importance to allied research field and industries in Canada as it will not only advance our fundamental knowledge of relativistic quantum mechanical phenomena in low dimensional systems but also help people overcome limitations in current semiconductor technology and prepare for post-silicon electronics. This research is also important to Canada as it involves information and communication technologies (ICT), nanotechnology, and energy technologies which are among the areas of R&D priority under Canada’s Science, Technology and Innovation Strategy.