Engineering graphene-based heterostructures for enhanced light detection

In recent years, research groups have been making significant strides towards developing more efficient and scalable photonic devices. There is a growing need for photonic devices that offer low power consumption and broad bandwidth detection. A great deal of interest has emerged around two-dimensional (2D) materials due to their exceptional properties. When 2D materials are stacked, they can exhibit several novel effects. Graphene, in particular, is ideally suited for optoelectronic and photonic applications because of its broad absorption range from the UV to the far-infrared spectrum, as well as its rapid electron excitation and relaxation dynamics. Many graphene-based photodetectors have been developed to achieve large bandwidth and fast response times. However, these devices typically require a voltage bias. A promising solution to achieve zero-bias current is to utilize a different current generation mechanism known as the photothermoelectric (PTE) effect. This effect occurs when there is both a spatial variation in temperature and in the Seebeck coefficient. The temperature variation can be induced by photon absorption in graphene, while the Seebeck coefficient can be modified through doping. One particularly exciting discovery is the permanent charge transfer induced in graphene by its proximity to alpha-RuCl3, a p-doping 2D material. RuCl3 creates an ultrasharp lateral junction that can be used to generate photocurrent via the PTE effect. This experimental thesis demonstrates the development of a highly responsive, zero-bias graphene-RuCl3 photodetector, achieving promising performances in the optical region.