Preparation of graphene, bismuth chalcogenide and their heterostructures with application in photonics and optoelectronics

Graphene, a novel 2-D allotrope form of carbon, has triggered intensive research interests in 2-D materials. 2-D materials’ extraordinary properties promise varies applications, such as electronics, optics and optoelectronics. Particularly, graphene and bismuth chalcogenides (Bi₂Se₃, Bi₂Te₃ et. al.), which share similar Dirac bandgap structures and exotic surface states, are outstanding candidates in potential applications of broadband optoelectronic, plasmonic devices and future on-chip devices. Though researchers have dedicated their efforts in the 2-D materials, the attention being paid to the graphene and bismuth chalcogenides based materials remains low, especially in their large production and optoelectronic device applications.
   This research dissertation starts with the preparation of high quality graphene, bismuth chalcogenide nanocrystals and their heterostructure. By taking advantages of the in situ Powder X-ray diffraction technique, better understanding in the growth mechanism of bismuth chalcogenides nanoplatelets and its graphene heterostructure has been obtained. Step by step growth mechanism is revealed and discussed. Thus large-scale prepared graphene and bismuth chalcogenides hybrid material has been integrated into a free standing thin film, which is further demonstrated as a broadband photodetector. On the other hand, it is found that the graphene and Bi₂Te₃ heterostructure films can effectively enhance plasmon resonance magnitude in its FTIR spectrum by increasing light-matter interactions. In order to better observe and understand the plasmonic resonance modes on these materials, the later sections of this dissertation investigated resonance modes on graphene surfaces from both far-field and near-field. The results show that the light-matter interaction can be further enhanced by modifying the geometry of the surface and the surface plasmon can be guided in a controlled manner. It is believed, this dissertation paves way for the photonic and optoelectronic researches of graphene, bismuth chalcogenides and their heterostructures.