Unravelling the terahertz electronic properties of graphene for applications in optoelectronics

石墨烯是以六方蜂窝晶格结构共价结合的碳原子单层。围绕石墨烯的兴奋源于其独特的机械，光学和电子性能，并提出了石墨烯的重大创新应用，如高灵敏度传感器，纳米电子学，高速光电子学和光电探测。然而，石墨烯的这种特殊性质也是一把双刃剑，使其特性容易因各种因素而改变。因此，合成具有所需特性的石墨烯仍然非常具有挑战性，特别是对于更复杂的情况，如双层石墨烯和石墨烯复合材料。将这些技术升级和优化到工业水平无疑是费力和低效的。显然，一种非接触、非破坏性的技术来表征石墨烯（如其电子特性）可以提供调整合成过程的方法，使人们能够有效地找到正确的配方。* 为此，我们在该战略项目中建议使用非线性太赫兹（THz）光谱对各种石墨烯样品的THz电子特性进行非接触，非破坏性表征。由于其低光子能量，THz辐射是理想的泵浦和探测石墨烯等无带材料中的载流子。非线性太赫兹光谱学是一种研究材料在强太赫兹辐射下行为的新技术。在这个项目中，我们将与两家加拿大公司合作，制造和表征各种类型的石墨烯样品，并在理论建模的支持下，更好地了解石墨烯的太赫兹电子特性。基于这些新知识，我们还将讨论石墨烯在未来设备中的可能应用。**

Graphene is a monolayer of carbon atoms covalently bound in a hexagonal honeycomb lattice structure. The excitement around graphene stems from its unique mechanical, optical and electronic properties, and significant innovative applications of graphene have been proposed, such as high-sensitivity sensors, nano-electronics, high-speed optoelectronics and photodetection. However, such exceptional properties of graphene are also a double-edged sword, allowing its characteristics to easily change due to various factors. As such, synthesizing graphene with the desired characteristics remains very challenging, especially for more complex cases like bilayer graphene and graphene composites. Upgrading such techniques and optimizing them to the industrial level would undoubtedly be laborious and inefficient. Clearly, a non-contact, non-destructive technique to characterize graphene (such as its electronic properties) could provide means to tweak the synthesizing process, allowing one to efficiently find the right recipe. ****To this end, we propose in this Strategic project to use nonlinear terahertz (THz) spectroscopy for non-contact, non-destructive characterization of the THz electronic properties of various graphene samples. Due to its low photon energy, THz radiation is ideal to pump and probe carriers in a bandless material like graphene. Nonlinear THz spectroscopy is a new technique that studies the behaviour of materials under intense THz irradiation. In this project, we will work with two Canadian companies to fabricate and characterize various types of graphene samples, and with the support of theoretical modelling, gain better understanding of the THz electronic properties of graphene. Based on this new knowledge, we will also address possible applications of graphene to future devices. **