Enhanced PdSe2/Si heterojunction photodetector by Al2O3 layer

PdSe2/Al2O3/Si heterojunction device was fabricated by inserting Al2O3 tunneling layer grown by atomic layer deposition (ALD) in order to decrease the dark current. A fast and broadband photodetector was realized by optimizing the thickness of Al2O3. Results showed that the dark current of PdSe2/Al2O3/Si device was reduced by about 3 orders of magnitude compared with the device without Al2O3 layer under 808 nm illumination and −2 V bias voltage. The photoresponsivity of the device was about 0.31 A/W and the corresponding specific detectivity was about 2.5×1012 Jones. The device exhibited obvious self-driving effect without bias. The device still maintained a better photoresponse after 1 200 cycles of cyclic testing. The rise time and fall time of photoresponse were 7.1 µs and 15.6 µs, respectively. The introduction of Al2O3 tunneling layer between the two-dimensional layered semiconductor material and silicon can effectively reduce the dark current of the device and is beneficial to achieving high-performance silicon-based photodetectors. © 2023 Zhejiang University. All rights reserved.