Graphene–MoS₂ hybrid structures for multifunctional photoresponsive memory devices

Abstract

Combining the electronic properties of grapheme^{1, 2} and molybdenum disulphide (MoS₂)^{3, 4, 5, 6} in hybrid heterostructures offers the possibility to create devices with various functionalities. Electronic logic and memory devices have already been constructed from graphene–MoS₂ hybrids^7,8, but they do not make use of the photosensitivity of MoS₂, which arises from its optical-range bandgap⁹. Here, we demonstrate that graphene-on-MoS₂ binary heterostructures display remarkable dual optoelectronic functionality, including highly sensitive photodetection and gate-tunable persistent photoconductivity. The responsivity of the hybrids was found to be nearly 1 × 10¹⁰ A W⁻¹ at 130 K and 5 × 10⁸ A W⁻¹ at room temperature, making them the most sensitive graphene-based photodetectors. When subjected to time-dependent photoillumination, the hybrids could also function as a rewritable optoelectronic switch or memory, where the persistent state shows almost no relaxation or decay within experimental timescales, indicating near-perfect charge retention. These effects can be quantitatively explained by gate-tunable charge exchange between the graphene and MoS₂ layers, and may lead to new graphene-based optoelectronic devices that are naturally scalable for large-area applications at room temperature.