Optimized responsivity of a phototransistor using graphene oxide-doped solution-processed indium oxide active layer toward neuromorphic applications

Abstract

Recently, metal oxide semiconductors have attracted considerable interest in certain areas, such as displays. Applications of transparent metal oxide semiconductors in photosensors are also starting to develop owing to their high charge carrier concentration and mobility. By including a narrow bandgap material in the device, photoresponsivity can be improved, but it increases the number of fabrication steps. This paper suggests embedding an indium oxide thin film with graphene oxide (GO) photoactive particles in a single step from a mixed aqueous precursor solution by spin coating. The device performance was assessed as a function of the GO content. The device stability data showed that a higher GO content induced hole trapping under prolonged gate bias stress. Hole trapping at the In₂O₃/GO interface is important under illumination, where the trapping of the minor photogenerated carrier can improve the photocurrent via the photogating effect. The long-term trapping of holes in the n-type device also produces a persistent photocurrent, which makes the device respond to illumination like an artificial neuron. In addition to photodetection, the device applicability in binary logic circuits was also demonstrated via a load-type inverter. The phototransistor proposed in this study could achieve sensing, memory, and binary logic in the same device.