A photodetector (400) has a two dimensional conductive channel (302, 408) with source and drain electrodes (404) configured to enable a flow of electrical current through the two dimensional conductive channel (302, 408); and a quantum dot layer (304, 406) overlying the two dimensional conductive channel (302, 408), the quantum dot layer (304, 406) configured to generate charge on exposure to incident electromagnetic radiation (310), the generated charge producing an electric field which causes a change in electrical current passing through the underlying two dimensional conductive channel (302, 408), the change in electrical current being indicative of one or more of the presence and magnitude of the incident electromagnetic radiation (310); wherein the quantum dot layer (304, 406) is configured to have an incident electromagnetic radiation surface (312) which has a texturing comprising undulations in the surface to provide a surface roughness with an average peak amplitude (308) of the order of between 10 nm and 300 nm. The surface texture increases the amount of electromagnetic radiation absorbed in the quantum dot layer (304, 406) in comparison to a photodetector having a flat (non-textured) incident electromagnetic radiation surface.