High photoresponsivity and external quantum efficiency of ultraviolet photodetection by mechanically exfoliated planar multi-layered graphene oxide sheet prepared using modified Hummer's method and spin coating technique

Abstract

Electron–hole (e–h) pair generation and conversion into photocurrents by two-dimensional (2D) nanoparticle based metal semiconductor metal (MSM) structured photodetector is crucial for the development self-powered and high performance photodetectors. In this regard, graphene oxide (GO) is a highly suitable photoconducting material alongside graphene and reduced graphene oxide (rGO). A modified Hummer's method is applied to obtain the GO supernatant which undergoes morphological, structural and vibrational characterizations. The D and G bands observed at 1347 and 1592 cm–1 from the spectral analysis are due to the A1g symmetry sp3 carbon (C) and E2g phonons by sp2 C respectively, confirming the formation of GO. Electron beam evaporation is carried out to fabricate the silver (Ag) source and drain electrode fringes with 300 nm separation for current– voltage characterization. Non-linear and non-rectifying behavior is observed on the MSM structured multilayer GO film. The ideality factor and barrier height, calculated from the thermionic emission model at the Schottky junction of source is found to be lower than that of the drain. The mechanically exfoliated GO onto the Ag electrodes enables a high photoresponsivity and external quantum efficiency (EQE) about 4.12 AW–1 and 1346% to be attained. This shows that GO can behave as either a p- or n-type semiconducting materials.