New photodiodes based graphene-organic semiconductor hybrid materials

Abstract

New photodiodes based graphene-organic semiconductor hybrid materials were fabricated for the first time using sol–gel spin coating technique. The current–voltage characteristics of the Au/GO:coumarin/p-Si/Al diodes were investigated under dark and various illumination intensities. The various junction parameters of the diodes were determined using I–V, C–V and transient characteristics. The transient photocurrent measurements indicate that Au/GO:coumarin/p-Si/Al diodes are very sensitive to illumination and the precise responsivity of the diodes is tunable by adjusting GO:coumarin fraction. The capacitance–voltage–frequency (C–V–f) measurements indicate that the capacitance of the diodes depends on voltage and frequency. The capacitance decreases with increasing frequency due to a continuous distribution of the interface states. The ability to tune the photosensitivity in the photoconductive mode through graphene oxide:coumarin weight ratio has been shown to lead to a near-constant sensitivity to illumination for a weight ratio of 0.03GO. The obtained results suggest that Au/GO:coumarin/p-Si/Al diodes can be used as a photosensor in optic communications.