2.3 Graphene and Related Materials
31
Fig. 2.8 a Sketch of the Förster resonant energy transfer (FRET) from an excited cQD exciton
mode to an electronically-doped graphene Dirac cone by backgate bias tuning. This configuration
was experimentally investigated with regard to backgate-dependent cQD-emission lifetime (i.e.
revealing FRET as a gate-tunable loss channel) as well as photodetector responsivity modifications.
b Schematic drawing of optically-excited cQDs of core/shell type with long ligands on a (laserdefined) graphene channel of a homemade field-effect transistor. a, b Reproduced under the terms
of the CC-BY 4.0 Licence (http://creativecommons.org/licenses/by/4.0/). [191] Copyright 2016
The Author(s), published by Springer Nature
dynamic range [178]. For instance, a monolithic integration of a CMOS integrated
circuit with graphene, operating as a high-mobility phototransistor, was recently
reported [179]. However, the weak light absorption limits its application for photodetection in the same broad spectral region where it relies on the states of its Dirac
cone of a single layer of ultrathin material.
Graphene Photodetection Schemes
In this context, a combination of graphene with an excellent light absorber has
been pursued for the fabrication of efficient graphene-based photodetectors. Several approaches including a graphene–semiconductor heterojunction [180–183], a
graphene pn-junction [184], quantum-dots–graphene hybrid detectors [185–192],
graphene–TMDC–graphene heterostructures [173, 193, 194] and many more were
reported recently.
Quantum-Dot Hybrid Systems with Graphene
Among these platforms, the colloidal quantum dots (cQDs) hybrid structure has
remained a promising candidate for photodetection schemes owing to the cQDs’
wavelength tunablility as well as their efficient light-absorbing capability. Therefore,
one aims at combining the optical advantages of cQDs together with the outstanding
electrical properties of graphene. Typically, optical power is absorbed by the layer of
cQDs on graphene and the excitation energy transferred to the graphene sheet. This
can lead to detectors with ultra-high gain and a high external quantum efficiency of
up to 25% [189]. In addition, the transfer rate can be manipulated by an applied gate
voltage [191, 195] (indicated for Förster resonant energy transfer schematically in
Fig. 2.8).
31
Fig. 2.8 a Sketch of the Förster resonant energy transfer (FRET) from an excited cQD exciton
mode to an electronically-doped graphene Dirac cone by backgate bias tuning. This configuration
was experimentally investigated with regard to backgate-dependent cQD-emission lifetime (i.e.
revealing FRET as a gate-tunable loss channel) as well as photodetector responsivity modifications.
b Schematic drawing of optically-excited cQDs of core/shell type with long ligands on a (laserdefined) graphene channel of a homemade field-effect transistor. a, b Reproduced under the terms
of the CC-BY 4.0 Licence (http://creativecommons.org/licenses/by/4.0/). [191] Copyright 2016
The Author(s), published by Springer Nature
dynamic range [178]. For instance, a monolithic integration of a CMOS integrated
circuit with graphene, operating as a high-mobility phototransistor, was recently
reported [179]. However, the weak light absorption limits its application for photodetection in the same broad spectral region where it relies on the states of its Dirac
cone of a single layer of ultrathin material.
Graphene Photodetection Schemes
In this context, a combination of graphene with an excellent light absorber has
been pursued for the fabrication of efficient graphene-based photodetectors. Several approaches including a graphene–semiconductor heterojunction [180–183], a
graphene pn-junction [184], quantum-dots–graphene hybrid detectors [185–192],
graphene–TMDC–graphene heterostructures [173, 193, 194] and many more were
reported recently.
Quantum-Dot Hybrid Systems with Graphene
Among these platforms, the colloidal quantum dots (cQDs) hybrid structure has
remained a promising candidate for photodetection schemes owing to the cQDs’
wavelength tunablility as well as their efficient light-absorbing capability. Therefore,
one aims at combining the optical advantages of cQDs together with the outstanding
electrical properties of graphene. Typically, optical power is absorbed by the layer of
cQDs on graphene and the excitation energy transferred to the graphene sheet. This
can lead to detectors with ultra-high gain and a high external quantum efficiency of
up to 25% [189]. In addition, the transfer rate can be manipulated by an applied gate
voltage [191, 195] (indicated for Förster resonant energy transfer schematically in
Fig. 2.8).