A device for direct X-ray detection (516) comprises a plurality of substantially parallel conductive channels (501) separated from one another by a quantum dot material (510), thereby forming a composite material layer (517). The parallel conductive channels (501) are electrically connected to source and drain electrodes (503 504a) which enable a flow of electrical current through the conductive channels (501). The quantum dot material (510) generates electron hole pairs upon exposure to incident electromagnetic radiation and the thus generated charge results in an electric field which causes a change in electrical current passing through at least one of the conductive channels (501). The change in electrical current is indicative of one or more of the presence and magnitude of the incident electromagnetic radiation. Since the conductive channels (501) are oriented in a direction perpendicular to the plane of the substrate (502), the distances between the conductive channels can be chosen under consideration of the diffusion lengths of the generated charge carriers and independently from the thickness of the composite material layer (517) required for X-ray radiation.