Light Helicity Dependent Photocurrent in Graphene Planes

In this chapter, specific phenomenology of second-order nonlinear-in-electric field-dependent photocurrents in graphene will be introduced together with the microscopic theories of the effects responsible for generation of such photocurrents, namely the photogalvanic and photon drag effects. Detailed analysis for the phenomenology and microscopic understanding will be provided with comparisons to various perspectives presented in the previous chapters, e.g. crystal symmetry and time reversal symmetry, as well as measurement geometry conditions. The nonlinear-in-electric field-dependent photocurrent data of graphene photodetectors and phototransistors (excluding the edge effects) available in literature will be discussed mainly in terms of photon energy excitation dependence, starting from classical to quantum frequency range.