Unravelling the terahertz electronic properties of graphene for applications in optoelectronics

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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.