Tuning of solution-processed rGO-MoS2 bi-film transistor characteristics by selective layer nitrogen-doping

Abstract

A novel technique for depositing wafer-scale bi-films of graphene oxide (GO) and MoS₂ with a thickness of 7 nm or less using the filter paper-assisted (FPA) method is present here. This method allows for the easy addition of a second layer without considering the nanosheet’s dimension or filter pore size. A GO density of 0.5 μg/cm² exhibited single-layer coverage, where approximately a 6 nm MoS₂ layer was deposited on GO. The resulting thin film was transferred onto a pre-patterned device. Reduced GO (rGO) and MoS₂ layers were selectively treated with low-power ammonia plasma for nitrogen(N)-doping, followed by transistor channel preparation using photolithography and dry-etching techniques. The N-doping of rGO resulted in highly n-type transistor characteristics of the MoS₂/rGO device prepared by the FPA method, improving electron mobility by 22.3 %. N-doping of MoS₂ caused a p-type shift in the direct point (by 5.2 V) of the bi-film device. Both the FPA thin film and the prepared devices displayed uniform characteristics across the wafer, indicating the scalability and uniformity achieved by the proposed FPA method.