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Wafer-scale Fabrication of Nitrogen-doped Reduced Graphene Oxide with Enhanced Quaternary-N for High-Performance Photodetection
摘要： We demonstrated a simple and scalable fabrication route of nitrogen-doped reduced graphene oxide (N-rGO) photodetector on 8-inch wafer-scale. The N-rGO was prepared through in-situ plasma-treatment in an acetylene-ammonia atmosphere to achieve n-type semiconductor with substantial formation of quaternary-N substituted into the graphene lattice. The morphology, structural, chemical composition and electrical properties of the N-rGO was carefully characterized and being used for the device fabrication. The N-rGO devices were fabricated in a simple metal-semiconductor-metal (MSM) structure with unconventional metal-on-bottom configuration to promote high-performance photodetection. The N-rGO devices exhibited enhanced photoresponsivity as high as 0.68 A W?1 at 1.0 V, which is about two orders of magnitude higher compared to a pristine graphene and wide-band photo-induced response from visible to near-infrared (NIR) region with increasing sensitivity in the order of 785 nm, 632.8 nm and 473 nm excitation wavelengths. We also further demonstrated a symmetric characteristic of photo-induced response to any position of local laser excitation with respect to the electrodes. The excellent features of wafer-scale N-rGO devices suggest a promising route to merge the current silicon technology and two-dimensional materials for future optoelectronic devices.
关键词： photodetector,plasma treatment,quaternary-N,wafer-scale fabrication,Nitrogen-doped reduced graphene oxide
更新于2025-09-23 15:23:52
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Wafer-Scale Fabrication of 2D PtS <sub/>2</sub> /PtSe <sub/>2</sub> Heterojunctions for Efficient and Broadband Photodetection
摘要： The fabrication of van der Waals heterostructures have mainly extends to two-dimensional materials that are exfoliated from their bulk counterparts, which is greatly limited by high-volume manufacturing. Here, we demonstrate multilayered PtS2/PtSe2 heterojunctions covering a large area on SiO2/Si substrate with a maximum size of 2" in diameter, offering throughputs that can meet the practical application demand. Theoretical simulation was carried out to understand the electronic properties of the PtS2/PtSe2 heterojunctions. Zero-bias photoresponse in the heterojunctions is observed under laser illumination of different wavelengths (405 to 2200 nm). The PtS2/PtSe2 heterojunctions exhibit broadband photoresponse, high quantum efficiency at infrared wavelengths with lower bounds for the external quantum efficiencies (EQE) being 1.2% at 1064 nm, 0.2% at 1550 nm and 0.05% at 2200 nm, and also relatively fast response time at the dozens of millisecond level. The large area, broadband 2D heterojunction photodetector demonstrated in this work further corroborating the great potential of 2D materials in the future low-energy optoelectronics.
关键词： van der Waals heterostructures,self-driving operation,quantum efficiency,broadband photodetection,photoresponsivity,wafer-scale fabrication
更新于2025-09-23 15:21:01
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Arrays of Plasmonic Nanoparticle Dimers with Defined Nanogap Spacers
摘要： Plasmonic molecules are building blocks of metallic nanostructures that give rise to intriguing optical phenomena with similarities to those seen in molecular systems. The ability to design plasmonic hybrid structures and molecules with nanometric resolution would enable applications in optical metamaterials and sensing that presently cannot be demonstrated, because of a lack of suitable fabrication methods allowing the structural control of the plasmonic atoms on a large scale. Here we demonstrate a wafer-scale ‘lithography-free’ parallel fabrication scheme to realize nanogap plasmonic meta-molecules with precise control over their size, shape, material, and orientation. We demonstrate how we can tune the corresponding coupled resonances through the entire visible spectrum. Our fabrication method, based on glancing angle physical vapor deposition with gradient shadowing, permits critical parameters to be varied across the wafer and thus is ideally suited to screen potential structures. We obtain billions of aligned dimer structures with controlled variation of the spectral properties across the wafer. We spectroscopically map the plasmonic resonances of gold dimer structures and show that they are not only in a good agreement with numerically modeled spectra, but also remain functional, at least for a year, in an ambient condition.
关键词： glancing angle deposition,wafer-scale nanofabrication,asymmetric shadow,nanophotonics,optical metamaterials,scalable plasmonics
更新于2025-09-12 10:27:22
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Wafer-scale single-crystal hexagonal boron nitride film via self-collimated grain formation
摘要： Although polycrystalline hexagonal boron nitride (PC-hBN) has been realized, defects and grain boundaries still cause charge scatterings and trap sites, impeding high-performance electronics. Here, we report a method of synthesizing wafer-scale single-crystalline hBN (SC-hBN) monolayer films by chemical vapor deposition. The limited solubility of boron (B) and nitrogen (N) atoms in liquid gold promotes high diffusion of adatoms on the surface of liquid at high temperature to provoke the circular hBN grains. These further evolve into closely packed unimodal grains by means of self-collimation of B and N edges inherited by electrostatic interaction between grains, eventually forming an SC-hBN film on a wafer scale. This SC-hBN film also allows for the synthesis of wafer-scale graphene/hBN heterostructure and single-crystalline tungsten disulfide.
关键词： single-crystalline,hexagonal boron nitride,wafer-scale,tungsten disulfide,chemical vapor deposition,graphene/hBN heterostructure
更新于2025-09-10 09:29:36
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Layer-Dependent Dielectric Function of Wafer-Scale 2D MoS <sub/>2</sub>
摘要： Wafer-scale, high-quality, and layer-controlled 2D MoS2 films on c-sapphire are synthesized by an innovative two-step method. The dielectric functions of MoS2 ranging from the monolayer to the bulk are investigated by spectroscopic ellipsometry over an ultra-broadband (0.73–6.42 eV). Up to five critical points (CPs) in the dielectric function spectra are precisely distinguished by CP analysis, and their physical origins are identified in the band structures with the help of first-principles calculations. Results demonstrate that the center energies of these CPs exhibit intriguing layer dependency, which are interpreted by the intrinsic layer-dependent transitions in MoS2. Specially, the change in the imaginary part of the dielectric functions versus the thickness exhibits a “W” like curve, and the two valley bottoms appear at about four-layer and 10-layer respectively. These complex fluctuations are attributed to the alternating domination of the decreasing excitonic effect, the increasing joint density of states, and the mass density increase in relative thick MoS2 samples.
关键词： layer-dependent dielectric function,two-step method,spectroscopic ellipsometry,wafer-scale 2D MoS2
更新于2025-09-10 09:29:36
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25 nm Single-Crystal Silicon Nanowires Fabricated by Anisotropic Wet Etching
摘要： We report a top-down method for fabricating ultra-high aspect ratio single-crystal silicon nanowires. The fabrication method is based on the standard photolithography technique and anisotropic wet etching of the single-crystal silicon in KOH solution. SiO2 mask nanolines used for patterning single-crystal silicon nanowires are formed by the undercut etching of thin SiO2 layer in buffered hydrofluoric solution. The minimum width of the SiO2 mask nanolines are 50 nm. The length of SiO2 mask nanolines is 2 cm. The single-crystal silicon nanowires have been successfully transferred from the SiO2 mask nanolines by KOH anisotropic wet-chemical etching. The minimum width of the silicon nanowire has obtained to be 25 nm. The fabricated single-crystal silicon nanowires have trapezoidal and triangular cross sections, which are useful for applications in nanoelectronic and nanophotonic elements.
关键词： All Wet Chemical Etching,Wafer-Scale Fabrication,Single-Crystal Silicon Nanowire,Photolithography
更新于2025-09-04 15:30:14