Graphene for Photodetectors and Optoelectronics

In optoelectronics, graphene has received a great deal of attention because of the unique anisotropic properties, where it has high mobilities of charge carriers, mechanical flexibility, and strong broadband absorption.Owing to its atomically thin structure, it is highly effective in its interaction with electromagnetic radiation with even the low intrinsic absorption in the wide electromagnetic spectrum, ultraviolet to terahertz.This chapter is about the fundamental optical properties of graphene and important aspects of those properties are linear dispersive nature, tunable conductivity, ultrafast responsiveness due to incident photons among the other aspects these properties form foundation of photodetection of graphene.Multiple photodetector designs based on graphene are discussed such as photoconductive and photovoltaic devices, hybrid designs where graphene is used in combination with semiconductors like silicon, quantum dots or layered transition metal dichalcogenides.All these combinations are used to improve photo response, minimize noise and widen spectral sensitivity.Quality of graphene significantly determines the performance of such devices and growth and transfer techniques such as chemical vapor deposition, as well as epitaxial techniques play an important role in the fabrication of such devices.In addition to material preparation, the chapter also mentions the role of lithographic method in the development of photodetector array and scaled device aspect.The consideration is made towards graphene integration into the transparent and flexible substrates, and this is a milestone towards bendable and wearable optoelectronic systems.The metrics are responsivity, response speed, and detectivity that are measured in detail to compare the performance of the graphene-based design with the traditional photodetector technologies.Examples of such practical usages of the devices result within the optical communication sphere, terahertz and infrared detection, and transparent or flexible sensing systems.During further development of the research, graphene has been placed as fundamental material capable of adding to the miniaturization, multifunctionality, and flexibility of semiconductor devices of today.

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