posted on 2024-03-12, 14:48authored byDong Wu, Wei He, Peng Yu, Guowei Yang
Response
time, an important parameter of the photodetectors, is
used to evaluate the ability to follow a fast-changing optical signal.
Various strategies, including the utilization of heterojunction and
homojunction detectors, have been implemented to improve the response
speed. However, high energy barriers restrict the operation of these
devices to either zero bias or reverse bias conditions. Herein, a
strategy is developed to modulate response speed, in which a two-dimensional
(2D) CuBiP2Se6 nanosheet is employed as a novel
van der Waals (vdWs) floating gate to enhance the response speed of
a 2D PdPSe-based photodetector. The huge difference between the work
functions of CuBiP2Se6 and PdPSe enables the
built-in field of the contact interface to significantly modulate
the surface barrier height of PdPSe, thus changing a Schottky contact
to an ohmic contact. Hence, our device yields an enhanced response
speed of 148 μs at both forward and reverse bias, faster than
the typical PdPSe device by more than 3 orders of magnitude and the
CuBiP2Se6/PdPSe heterostructure device by 3
times. In addition, our device also presents a high responsivity of
370 A/W. Interestingly, imaging and polarized light detection endow
our device with broad prospects in future micro- or nano-optoelectronic
devices. Our work provides a promising strategy toward next-generation
ultrafast photodetectors.