Broken-gap
van der Waals (vdW) heterojunctions based on 2D materials
are promising structures to fabricate high-speed switching and low-power
multifunctional devices thanks to its charge transport versus quantum tunneling mechanism. However, the tunneling current is usually
generated under both positive and negative bias voltage, resulting
in small rectification and photocurrent on/off ratio. In this paper,
we report a broken-gap vdW heterojunction PtS2/WSe2 with a bilateral accumulation region design and a big band
offset by utilizing thick PtS2 as an effective carrier-selective
contact, which exhibits an ultrahigh reverser rectification ratio
approaching 108 and on/off ratio over 108 at
room temperature. We also find excellent photodetection properties
in such a heterodiode with a large photocurrent on/off ratio over
105 due to its ultralow forward current and a comparable
photodetectivity of 3.8 × 1010 Jones. In addition,
the response time of such a photodetector reaches 8 μs owing
to the photoinduced tunneling mechanism and reduced interface trapping
effect. The proposed heterojunction not only demonstrates the high-performance
broken-gap heterodiode but also provides in-depth understanding of
the tunneling mechanism in the development of future electronic and
optoelectronic applications.
PdSe2, a star photosensitive functional material, has been successfully used in photodetectors based on sensing mechanisms of photogating, photoconductive, and photovoltaic effects. Here, a photothermoelectric (PTE) effect is observed in photodetectors based on PdSe2 flakes grown by chemical vapor deposition. The unique photoresponse arises from an electron temperature gradient instead of electron–hole separation. Direct evidence of the PTE effect is confirmed by a nonlocal photoresponse under zero bias. Moreover, the PdSe2 photodetector shows high performance in terms of ultrafast response speed (4 µs), high air‐stability, broadband spectrum photodetection, reasonable responsivity, and anisotropic optical response. This study paves a new way for developing high‐performance photodetectors based on PdSe2 layered materials.
2D
material (2DM) based photodetectors with broadband photoresponse
are of great value for a vast number of applications such as multiwavelength
photodetection, imaging, and night vision. However, compared with
traditional photodetectors based on bulk material, the relatively
slow speed performance of 2DM based photodetectors hinders their practical
applications. Herein, a submicrosecond-response photodetector based
on ternary telluride InSiTe3 with trigonal symmetry and
layered structure was demonstrated in this study. The InSiTe3 based photodetectors exhibit an ultrafast photoresponse (545–576
ns) and broadband detection capabilities from the ultraviolet (UV)
to the near-infrared (NIR) optical communication region (365–1310
nm). Besides, the photodetector presents an outstanding reversible
and stable photoresponse in which the response performance remains
consistent within 200 000 cycles of switch operation. These
significant findings suggest that InSiTe3 can be a promising
candidate for constructing fast response broadband 2DM based optoelectronic
devices.
Pure and Fe-doped HoCrO3 and DyCrO3 powders were examined for the magnetocaloric properties with promising relative cooling power (RCP) values indicating their potential for applications in magnetic refrigeration.
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