  We report an improved photosensitivity in few-layer tin disulfide (SnS2)
field-effect transistors (FETs) following doping with CdSe/ZnS core/shell
quantum dots (QDs). The hybrid QD-SnS2 FET devices achieve more than 500
percent increase in the photocurrent response compared with the starting
SnS2-only FET device and a spectral responsivity reaching over 650 A/W at 400
nm wavelength. The negligible electrical conductance in a control QD-only FET
device suggests that energy transfer between QDs and SnS2 is the main mechanism
responsible for the sensitization effect, which is consistent with the strong
spectral overlap between QD photoluminescence and SnS2 optical absorption as
well as the large nominal donor-acceptor interspacing between QD core and SnS2.
We also find an enhanced charge carrier mobility in hybrid QD-SnS2 FETs which
we attribute to a reduced contact Schottky barrier width due to an elevated
background charge carrier density.
