Hybrid graphene-PbS quantum dot devices are fabricated on an n-type silicon substrate capped with a thin SiO2 layer and are characterized by photoelectrical measurements. It is shown that the resistance of the graphene channel in the devices exhibits detectable changes when a laser beam is switched on and off on the quantum dots. The model that explains the observed photoresponse phenomenon is illustrated. We also show that the photoresponse signal, i.e., the photoinduced change in the resistance of the graphene channel can be tuned in both magnitude and sign with a voltage applied to the back gate of the devices and is related to the derivative of the transfer characteristics of the graphene channel. Our work shows that the simple hybrid graphene-PbS quantum dot devices can be employed for photodetection applications.

The hybrid graphene-quantum dot devices can potentially be used to tailor the electronic, optical, and chemical properties of graphene. Here, the low temperature electronic transport properties of bilayer graphene decorated with PbS colloid quantum dots (CQDs) have been investigated in the weak or strong magnetic fields. The presence of the CQDs introduces additional scattering potentials that alter the magnetotransport properties of the graphene layers, leading to the observation of a new set of magnetoconductance oscillations near zero magnetic field as well as the high-field quantum Hall regime. The results bring about a new strategy for exploring the quantum interference effects in two-dimensional materials which are sensitive to the surrounding electrostatic environment, and open up a new gateway for exploring the graphene sensing with quantum interference effects.