In this study, a highly sensitive and self-driven near-infrared (NIR) light
photodetector based on PdSe2/pyramid Si heterojunction arrays, which
are fabricated through simple selenization of predeposited Pd nanofilm on
black Si, is demonstrated. The as-fabricated hybrid device exhibits excellent
photoresponse performance in terms of a large on/off ratio of 1.6 × 105,
a responsivity of 456 mA W−1, and a high specific detectivity of up to
9.97 × 1013 Jones under 980 nm illumination at zero bias. Such a relatively
high sensitivity can be ascribed to the light trapping effect of the pyramid
microstructure, which is confirmed by numerical modeling based on finitedifference
time domain. On the other hand, thanks to the broad optical
absorption properties of PdSe2, the as-fabricated device also exhibits obvious
sensitivity to other NIR illuminations with wavelengths of 1300, 1550, and
1650 nm, which is beyond the photoresponse range of Si-based devices.
It is also found that the PdSe2/pyramid Si heterojunction device can also
function as an NIR light sensor, which can readily record both “tree” and
“house” images produced by 980 and 1300 nm illumination, respectively.