Graphene/Si-quantum-dot heterojunction diodes showing high photosensitivity compatible with quantum size effect
We demonstrate quantum size effect (QCE) of Si quantum dots (SQDs) in the device level under the detailed size variation, very promising for realizing the optoelectronic device applications of SQDs. For this, we report first fabrication of graphene/SQDs-embedded SiO2 multilayers (SQDs:SiO2 MLs)-heterojunction structures that work as photodetectors (PDs) showing high performances very sensitive to the variations in size of SQDs as well as in doping concentration of graphene. The observed unique PD characteristics prove to be dominated by the tunneling of charge carriers across the SQDs:SiO2 MLs, based on bias-, size-, and doping-dependent variations of the band profiles, resulting in novel dark- and photo-current behaviors.
Keywords: graphene, Si quantum dot, photodetectors, tunneling, quantum size effect