All-Printable ZnO Quantum Dots/Graphene van der Waals Heterostructures for Ultrasensitive Detection of Ultraviolet Light.
In ZnO quantum dot/graphene heterojunction photodetectors, fabricated by printing quantum dots (QDs) directly on the graphene field-effect transistor (GFET) channel, the combination of the strong quantum confinement in ZnO QDs and the high charge mobility in graphene allows extraordinary quantum efficiency (or photoconductive gain) in visible-blind ultraviolet (UV) detection. Key to the high performance is a clean van der Waals interface to facilitate an efficient charge transfer from ZnO QDs to graphene upon UV illumination. Here, we report a robust ZnO QD surface activation process and demonstrate that a transition from zero to extraordinarily high photoresponsivity of 9.9 × 108A/W and a photoconductive gain of 3.6 × 109can be obtained in ZnO QDs/GFET heterojunction photodetectors, as the ZnO QDs surface is systematically engineered using this process. The high figure-of-merit UV detectivity D* in exceeding 1 × 1014Jones represents more than 1 order of magnitude improvement over the best reported previously on ZnO nanostructure-based UV detectors. This result not only sheds light on the critical role of the van der Waals interface in affecting the optoelectronic process in ZnO QDs/GFET heterojunction photodetectors but also demonstrates the viability of printing quantum devices of high performance and low cost.
Department of Physics and Astronomy, University of Kansas , Lawrence, Kansas 66045, United States.
Maogang
0000-0002-2031-781X
M
Gong
Department of Physics and Astronomy, University of Kansas , Lawrence, Kansas 66045, United States.
Qingfeng
Q
Liu
Department of Physics and Astronomy, University of Kansas , Lawrence, Kansas 66045, United States.
Brent
B
Cook
Department of Physics and Astronomy, University of Kansas , Lawrence, Kansas 66045, United States.
Bhupal
B
Kattel
Department of Physics and Astronomy, University of Kansas , Lawrence, Kansas 66045, United States.
Ti
T
Wang
Department of Physics and Astronomy, University of Kansas , Lawrence, Kansas 66045, United States.
Wai-Lun
0000-0001-8697-9894
WL
Chan
Department of Energy's National Security Campus , Kansas City, Missouri 64147, United States.
Dan
D
Ewing
Department of Energy's National Security Campus , Kansas City, Missouri 64147, United States.
Matthew
M
Casper
Department of Energy's National Security Campus , Kansas City, Missouri 64147, United States.
Alex
A
Stramel
Department of Physics and Astronomy, University of Kansas , Lawrence, Kansas 66045, United States.
Judy Z
JZ
Wu
graphene; interface; nanohybrids; printable ultraviolet photodetectors; van der Waals heterostructures; zinc oxide quantum dots