Optically active heterostructures of graphene and ultrathin MoS2

• We fabricate ultrathin (<10nm) heterostructure of graphene and MoS2.
• MoS2 in the hybrid induces persistent optical activity (PPC) in graphene.
• The ‘gate-erasable’ PPC shows more than 95% stability even after several hours.
• Cyclic switching operation of theses hybrids is possible using light and gate pulses.

Here we present the fabrication and characterization of a new class of hybrid devices where the constituents are graphene and ultrathin molybdenum di-sulphide (MoS2). This device is one of the simplest member of a family of hybrids where the desirable electrical characteristics of graphene such as high mobility are combined with optical activity of semiconductors. We find that in the presence of an optically active substrate, considerable photoconductivity is induced in graphene which is persistent up to a time scale of at least several hours. This photo induced memory can be erased by the application of a suitable gate voltage pulse. This memory operation is stable for many cycles. We present a theoretical model based on localized states in MoS2 which explains the data.