Due to the increasing demand for miniaturization and portability, the development of self-powered photodetectors that can work without external power supply has aroused great interest among researchers. As a group-10 layered transitional metal dichalcogenides, PtSe2 exhibits potential applications in photoelectric detection because of the unique properties such as high carrier mobility, tunable bandgap, and stability. However, its inherent large dark current hinders the further improvement of the performance of the PtSe2 photodetectors. In this paper, we fabricated a vertically aligned Two-dimensional (2D) van der Waals (vdWs) heterojunction composed of PtSe2 and MoSe2, which exhibits high sensitivity photoelectric detection performance in a wide band from visible light (405 nm) to near-infrared (1550 nm) without external bias. As a result, working in self-driving mode at room temperature, the responsivity and detectivity can reach 22.95 A W-1 and 9.27×1011 Jones with a fast response speed of 180/48 μs. This work is expected to provide a new idea for broadband, energy-efficient and high-performance miniaturized detectors.
Influenced by the prominent progress of two-dimensional (2D) layered crystals, the fabrication of 2D nanostructures from non-layered materials has attracted more and more attention. Lead selenide (PbSe) is one of the superior candidate materials for photodetector with suitable bandgap and outstanding photoelectric properties. The growth and device preparation of PbSe supply great interest for the development of high-performance infrared photodetectors. Although a lot of efforts have been paid on preparing PbSe nanostructures for miniaturized detectors, it is challenging to synthesize excellent crystallinity and thin 2D PbSe nanosheets because of itsinherent rock salt nonlayered structure. In this work, we employ a catalyst-free facile physical vapor deposition (PVD) method for controllable synthesis of PbSe nanosheets by van der Waals epitaxy technology. By optimizing the growth temperature, PbSe nanosheets from triangular pyramid island to square 2D plane can be obtained. In addition, the 2D PbSe nanosheets detector has a responsivity of 3.03 A/W at the wavelength of 520 nm with the power density of 5.05 mW/cm2. This work provides a facile strategy to synthesize high-quality 2D PbSe nanosheets which have enormous potentials to fabricate high-performance miniaturized photodetector.
In the field of electronic modulation, vanadium dioxide (VO2) is a potential material owing to its function of automatic insulator-to-metal transition (MIT) which can induce rapid changes in electrical resistivity through MIT. Nevertheless, the application of modulator based on VO2 is limited by some performance shortcomings, including wide hysteresis loop width (ΔH), high phase transition temperature (Tc) as well as low phase transition amplitude (AMIT). In this work, by DC (DirectCurrent)-magnetron sputtering with doping Fe3+ into VO2 films, narrowed ΔH and decreased Tc are observed. Interestingly, the Fe doped VO2 films show ultra-high phase transition amplitude despite the low Tc due to the influence of Fe dopants. Specifically, the 0.5% Fe-doped VO2 film shows the best MIT characteristics with ultra-high phase transition amplitude of 104, narrow ΔH decreased to 9.8° and low Tc around 60.02°C, which is considered to be the first time to highly heighten the electrical MIT properties by Fe doping. In addition, we also comprehensively studied the influences of doping with Fe element on the MIT properties and microstructures based on characterization such as SEM, XRD, Raman shift and XPS results. These results show that our unique preparation method can manufacture VO2 thin films with excellent MIT properties, which will be beneficial to the popularization and publicity of VO2 based electrical modulator.
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