ABSTRACT
Graphene nanomesh (GNM)-based optoelectronics integrated with quantum dots (QDs) are investigated in this article. The charge transfer mechanism in the QDs/GNM interface is probed in four terminal gated FET-type photodetectors. The insulating ligand is used to make the GNM/ligand/QDs vertically behave like a metal/insulate/semiconductor (MIS) structure to facilitate the charge tunnelling. With the current constraint effect of the GNM and the effective charge tunnelling, a high-performance photodetector is fabricated with higher responsivity, higher on/off ratio and shorter response time. The results of our analysis and experimental approach can be extended to future graphene-based photodetectors, as long as suitable ligands and an effective architecture are chosen for this type of device.
ABSTRACT
A novel size-controllable germanium quantum dot (Ge QD) is synthesized and decorated onto reduced graphene oxide (RGO) fragments to overcome the low infrared (IR) photoresponses (â¼0.1 A/W)13,14 of pristine graphene. With the integration of flexible substrate, monolayer graphene (MLG) electrode and n-type zinc oxide (ZnO), a high-performance QD-decorated-RGO/ZnO heterostructure infrared photodetector is reported in this study. The Ge QD-decorated-RGO hybrid photosensitive composite improves the responsivity (â¼9.7 A/W, 1400 nm) in IR waveband without sacrificing the response speed (â¼40 µs rise time and 90 µs recovery time). In addition, the effective barrier formed between graphene and ZnO interface restricts the dark current (â¼1.4 nA, -3 V) to guarantee the relatively excellent rectifying behavior and high on/off ratio (â¼10(3)) for this IR photodetector. With these superior inherent properties and micron-sized sensing active area, this photodetector manifests great potential in the future application of graphene-based IR photodetector.
