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Mixed-dimensional PdSe <sub/>2</sub> /SiNWA heterostructure based photovoltaic detectors for self-driven, broadband photodetection, infrared imaging and humidity sensing
摘要： The new discovery of two-dimensional (2D) palladium diselenide (PdSe2) films has attracted intensive research interest due to their unique asymmetric crystal structure and extraordinary optoelectronic properties, showing great potential for broadband and polarization photodetection. Herein, we have developed for the first time a self-driven, highly polarization-sensitive, broadband photovoltaic detector based on a PdSe2/Si nanowire array (SiNWA) heterostructure. Owing to the strong light confinement effect of the SiNWA and broadband light absorption of PdSe2, the present device exhibits pronounced photovoltaic behavior and excellent performance in terms of a high responsivity of 726 mA W?1, a large specific detectivity of 3.19 × 1014 Jones, an ultrabroad spectrum response range of 0.2–4.6 mm, and a fast response speed to monitor nanosecond pulsed light signals. Significantly, an impressive polarization sensitivity of 75 is achieved for the heterostructure device, which is among the highest for 2D material-based photodetectors. Thanks to the outstanding imaging capability, the detector can record images in both near infrared (NIR) and mid-infrared (MIR) ranges with a decent resolution. Moreover, the device exhibits light-enhanced humidity sensing behavior with a high sensitivity and a fast response/recovery time. Given these remarkable device features, the PdSe2/SiNWA heterostructure will hold great promise for high-performance, polarization-sensitive broadband photodetection, infrared imaging and humidity sensing applications.
关键词： humidity sensing,SiNWA,infrared imaging,photovoltaic detector,heterostructure,broadband photodetection,PdSe2
更新于2025-09-19 17:13:59
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Striated 2D Lattice with Sub‐nm 1D Etch Channels by Controlled Thermally Induced Phase Transformations of PdSe <sub/>2</sub>
摘要： 2D crystals are typically uniform and periodic in-plane with stacked sheet-like structure in the out-of-plane direction. Breaking the in-plane 2D symmetry by creating unique lattice structures offers anisotropic electronic and optical responses that have potential in nanoelectronics. However, creating nanoscale-modulated anisotropic 2D lattices is challenging and is mostly done using top-down lithographic methods with ≈10 nm resolution. A phase transformation mechanism for creating 2D striated lattice systems is revealed, where controlled thermal annealing induces Se loss in few-layered PdSe2 and leads to 1D sub-nm etched channels in Pd2Se3 bilayers. These striated 2D crystals cannot be described by a typical unit cells of 1–2 ? for crystals, but rather long range nanoscale periodicity in each three directions. The 1D channels give rise to localized conduction states, which have no bulk layered counterpart or monolayer form. These results show how the known family of 2D crystals can be extended beyond those that exist as bulk layered van der Waals crystals by exploiting phase transformations by elemental depletion in binary systems.
关键词： Se vacancies,Pd2Se3,2D crystals,PdSe2,STEM,1D channels
更新于2025-09-19 17:13:59
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Direct Laser Patterning and Phase Transformation of 2D PdSe <sub/>2</sub> Films for On-Demand Device Fabrication
摘要： Heterophase homojunction formation in atomically thin 2D layers is of great importance for next-generation nanoelectronics and optoelectronics applications. Technologically challenging, controllable transformation between the semiconducting and metallic phases of transition metal chalcogenides is of particular importance. Here, we demonstrate that controlled laser irradiation can be used to directly ablate PdSe2 thin films using high power or trigger the local transformation of PdSe2 into a metallic phase PdSe2?x using lower laser power. Such transformations are possible due to the low decomposition temperature of PdSe2 and a variety of stable phases compared to other 2D transition metal dichalcogenides. Scanning transmission electron microscopy is used to reveal the laser-induced Se-deficient phases of PdSe2 material. The process sensitivity to the laser power allows patterning flexibility for resist-free device fabrication. The laser-patterned devices demonstrate that a laser-induced metallic phase PdSe2?x is stable with increased conductivity by a factor of about 20 compared to PdSe2. These findings contribute to the development of nanoscale devices with homojunctions and scalable methods to achieve structural transformations in 2D materials.
关键词： device fabrication,phase transformation,PdSe2,FET,laser patterning,2D materials,graphene
更新于2025-09-12 10:27:22