Graphene Channels Interfaced with Quantum Dots in Field Effect Transistors: Electrical and Photo-Induced Effects

Graphene-based field effect transistors (GFETs) were assessed when interfaced with well separated and precisely placed core/shell CdSe/ZnS semiconductor quantum dot (QD) arrays. The QDs were imbedded in a hexagonal hole-array, which was formed in a layer of anodized aluminum oxide on Si/SiO2 substrates. Graphene (single, or two layers), grown by chemical vapor deposition (CVD) on Cu foils, was transferred and placed on top of the QDs imbedded films and served as the transistor channel. Electrical characteristics under white-light illumination at various biasing conditions revealed that the photo current was decreasing upon increasing biasing. The device's photoluminescence (PL) as a function of both the drain-source and gate-source potentials also reduced as a function of the potential biases. We observed two maxima in the PL data while tilting the sample with respect to the incident laser beam. We attributed it to the optimal coupling between the incident and the emission wavelengths to resonating surface modes.