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Hybrid dual-channel phototransistor based on 1D t-Se and 2D ReS2 mixed-dimensional heterostructures
摘要： The combination of mixed-dimensional semiconducting materials can provide additional freedom to construct integrated nanoscale electronic and optoelectronic devices with diverse functionalities. In this work, we report a high-performance dual-channel phototransistor based on one-dimensional (1D)/two-dimensional (2D) trigonal selenium (t-Se)/ReS2 heterostructures grown by chemical vapor deposition. The injection and separation efficiency of photogenerated electron–hole pairs can be greatly improved due to the high-quality interfacial contact between t-Se nanobelts and ReS2 films. Compared with bare ReS2 film devices, the dual-channel phototransistor based on t-Se/ReS2 heterostructure exhibits considerable enhancement with the responsivity (R) and detectivity (D*) up to 98 A·W–1 and 6 × 1010 Jones at 400 nm illumination with an intensity of 1.7 mW·cm?2, respectively. Besides, the response time can also be reduced by three times of magnitude to less than 50 ms due to the type-II band alignment at the interface. This study opens up a promising avenue for high-performance photodetectors by constructing mixed-dimensional heterostructures.
关键词： phototransistor,van der Waals heterostructures,ReS2,trigonal selenium (t-Se) nanobelt
更新于2025-09-23 15:23:52
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Temperature Dependence of Phonon Modes, Optical Constants, and Optical Band Gap in Two-Dimensional ReS2 Films
摘要： Effects of temperature on the optical properties of the large area ReS2 films (ten layers), which is prepared by chemical vapor deposition on SiO2/Si substrates, have been investigated by Raman and reflectance spectra. The phonon frequencies of eighteen Raman modes redshift about 3 cm-1 with increasing the temperature from 140 K to 320 K. The optical constants (n and k) at a photon energy region of 0.46-6.52 eV are obtained, and the values blue-shift with increasing temperature. Four interband transitions (Ep1, Ep2, Ep3, and Ep4) are observed at 1.53 eV, 2.98 eV, 4.25 eV, and 5.37 eV at 303 K, and the values increase with increasing the temperature. The physical origins have been assigned to the different band-to-band direct electronic transitions. The optical band gap of the ReS2 films increases from 1.36 eV at 303 K to 1.38 eV at 383 K. Based on the first-principles calculation results, the band gap increases from 1.32 eV at a normal lattice constant to 1.40 eV at 1.1 times lattice constant. This is because the energy levels present the tendencies of degeneracy, which due to the coupling between Re 5d orbital and S 3p orbital is weaker and the energy level splitting is smaller with increasing temperature.
关键词： optical constants,ReS2 films,2D materials,phonon modes,optical band gap
更新于2025-09-23 15:21:01
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Broadband polarized photodetector based on p-BP/n-ReS <sub/>2</sub> heterojunction
摘要： Two-dimensional (2D) atomic crystals, such as graphene, black phosphorus (BP) and transition metal dichalcogenides (TMDCs) are attractive for use in optoelectronic devices, due to their unique crystal structures and optical absorption properties. In this study, we fabricated BP/ReS2 van der Waals (vdWs) heterojunction devices. The devices realized broadband photoresponse from visible to near infrared (NIR) (400–1800 nm) with stable and repeatable photoswitch characteristics, and the photoresponsivity reached 1.8 mA/W at 1550 nm. In addition, the polarization sensitive detection in the visible to NIR spectrum (532–1750 nm) was demonstrated, and the photodetector showed a highly polarization sensitive photocurrent with an anisotropy ratio as high as 6.44 at 1064 nm. Our study shows that van der Waals heterojunction is an effective way to realize the broadband polarization sensitive photodetection, which is of great significance to the realization and application of multi-functional devices based on 2D vdWs heterostructures.
关键词： broadband,polarized photodetection,vdWs heterojunction,p-BP/n-ReS2
更新于2025-09-19 17:13:59
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Nd:YSAG Q-switched laser with anisotropic ReS2 nanosheets
摘要： We have demonstrate the preparation and characterization of the ReS2 nanosheet based saturable absorber and its applications in Nd:YSAG lasers. In addition, the anisotropic property of the ReS2 nanosheets 1.06 μm was discussed in detail. Our results show that the ReS2 could be used as a saturable absorber in solid state lasers and the intrinsic anisotropy at infrared wavelength range could also be used as a polaroid. The ReS2 nanosheets combined the applications of saturable absorber and polarizer could be used as excellent opto-electronic devices.
关键词： passively Q-switched,Nd:YSAG,ReS2,anisotropy
更新于2025-09-19 17:13:59
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Controllable Synthesis of Crystalline ReS <sub/>2(1?</sub><i> <sub/>x</sub></i> <sub/>)</sub> Se <sub/>2</sub><i> <sub/>x</sub></i> Monolayers on Amorphous SiO <sub/>2</sub> /Si Substrates with Fast Photoresponse
摘要： Re-based transition metal dichalcogenides (TMDs) and alloys have many unusual features such as in-plane anisotropic optical, electrical, and phonon properties and thus receive increasing research interest. However, the distorted 1T structure and the weaker interlayer coupling easily cause anisotropic growth and out-of-plane growth, making it particularly challenging to produce Re-based TMD and alloy monolayers on amorphous SiO2/Si substrates. Here, a reliable method is developed for the synthesis of high-quality and large-size ReS2(1?x)Se2x monolayer crystals on SiO2/Si substrates by NaCl-assisted, confined-space chemical vapor deposition. The synergy of salt assistance with the confined reaction space facilitates the formation of intermediate metal oxychlorides and creates a relatively stable growth environment, finally leading to the successful synthesis of ReS2(1?x)Se2x monolayer crystals on SiO2/Si substrates. The as-grown ReS2(1?x)Se2x monolayer alloys exhibit continuously variable composition, high crystal quality, and uniform distribution of Re, S, and Se elements. Furthermore, the ReS2(1?x)Se2x based photodetectors display good photoresponse to visible and near-infrared light with a fast response of less than 15 ms. The salt-assisted, confined-space chemical vapor deposition provides a reliable way for the synthesis of large-scale low-lattice symmetry 2D materials on amorphous SiO2/Si substrates and opens up new prospects for Re-based TMDs and alloys in optoelectronic devices.
关键词： ReS2(1?x)Se2x monolayers,NaCl,chemical vapor deposition,confined-space,photoresponse
更新于2025-09-12 10:27:22
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Photogating and high gain in ReS <sub/>2</sub> field-effect transistors
摘要： Two-dimensional layered transition metal dichalcogenides have shown much promise due to their remarkable electro-optical properties and potential use as photodetectors. We observed photogating in our few-layered (3–4 layers) ReS2 field-effect transistors (FETs) in which varying the incident optical power shifted the FETs’ threshold voltage. The photogating effect produced a significant gain in the electrical response of the FETs to incident light as measured by the responsivity (R) and external quantum efficiency (EQE). We obtained a maximum R of 45 A/W corresponding to an EQE of ～10 500% in a four-terminal measurement of the photoconductivity in the ON-state. We attribute both the photogating and the observed gain to the influence of charge traps. An estimate of the device gain based on our observations is calculated to be 5 × 104. Published by AIP Publishing.
关键词： photodetectors,high gain,charge traps,ReS2,field-effect transistors,photogating
更新于2025-09-10 09:29:36
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Fast identification of crystalline orientation of anisotropic two-dimensional materials using scanning polarization modulation microscopy
摘要： In this work, we have demonstrated that scanning polarization modulation microscopy (SPMM) provides a fast method for the identification of crystalline orientation of anisotropic two-dimensional (2D) materials. Using home-built 532 nm excited transmission SPMM, we identified the crystalline orientation of 2D orthorhombic black phosphorus, monoclinal 1T0-MoTe2, and triclinic ReS2 by measuring signals in only two incident polarization directions. So, it took just a few seconds to identify the crystalline orientation of anisotropic 2D materials. Our studies revealed that the SPMM method could be applied to arbitrary anisotropic 2D materials when selecting a suitable wavelength.
关键词： black phosphorus,1T0-MoTe2,scanning polarization modulation microscopy,anisotropic two-dimensional materials,ReS2,crystalline orientation
更新于2025-09-10 09:29:36
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Monolayer-ReS2 field effect transistor using monolayer-graphene as electrodes
摘要： Atomic thinness, excellent transport property and gate-tunable band structure of graphene render it a potential electrode material for assembling ultra thin electronic devices. Here, we present back gate field effect transistor based on exfoliated monolayer (ML) ReS2 as channel semiconductor and exfoliated ML-graphene as drain-source electrodes. The G and 2D peaks of ML-graphene stiffen significantly and their intensity ratio increases as well when the graphene is encapsulated between the SiO2/Si substrate and ReS2. Owing to the excellent electron transport properties of the ML-ReS2 and gate-tunable Fermi-level of the underlying ML-graphene, the transistor exhibits on/off current ratio exceeding 106, mobility of ~1.1 cm2V-1s-1 and subthreshold swing ~740 mV per decade. This work indicates that ML-graphene is an excellent electrode material for fabricating atomically thin ReS2 electronic devices.
关键词： Field effect transistor,Graphene,2D materials,ReS2
更新于2025-09-09 09:28:46
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Ion Beam Defect Engineering on ReS <sub/>2</sub> /Si Photocathode with Significantly Enhanced Hydrogen Evolution Reaction
摘要： Loading 2D layered transition metal dichalcogenides (TMDs) on p-type silicon photocathode is suitable for hydrogen production in solar-driven photoelectrochemical (PEC) water splitting. Similarly, various nanostructured TMDs exposing more active sites are widely explored for improving the PEC performances of composite photoelectrodes. Here, defect engineering using a controllable argon ion beam bombardment is presented on ReS2/Si photocathode. The atomic vacancy defects are introduced on the 2D ReS2 to realize high-density active sites, which significantly enhance the solar-driven hydrogen evolution reaction performance of ReS2/Si photocathode. The highest photocurrent density of 18.5 mA cm?2 (at 0 V vs reversible hydrogen electrode) is achieved, under a simulated sun irradiation.
关键词： ion beam bombardment,defect engineering,photocathodes,photoelectrochemical water splitting,ReS2
更新于2025-09-09 09:28:46
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Probing the upper band gap of atomic rhenium disulfide layers
摘要： Here, we investigate the ultrafast carrier dynamics and electronic states of exfoliated ReS2 films using time-resolved second harmonic generation (TSHG) microscopy and density functional theory (DFT) calculations. The second harmonic generation (SHG) of layers with various thicknesses is probed using a 1.19-eV beam. Up to ~13 nm, a gradual increment is observed, followed by a decrease caused by bulk interferometric light absorption. The addition of a pump pulse tuned to the exciton band gap (1.57 eV) creates a decay-to-rise TSHG profile as a function of the probe delay. The power and thickness dependencies indicate that the electron–hole recombination is mediated by defects and surfaces. The two photon absorptions of 2.38 eV in the excited state that are induced by pumping from 1.57 to 1.72 eV are restricted because these transitions highly correlate with the forbidden d–d intrasubshell orbital transitions. However, the combined usage of a frequency-doubled pump (2.38 eV) with wavelength-variant SHG probes (2.60–2.82 eV) allows us to vividly monitor the variations in TSHG profiles from decay-to-rise to rise-to-decay, which imply the existence of an additional electron absorption state (s-orbital) at an approximate distance of 5.05 eV from the highest occupied molecular orbital states. This observation was critically examined by considering the allowance of each electronic transition and a small upper band gap (~0.5 eV) using modified DFT calculations.
关键词： density functional theory,ReS2,time-resolved spectroscopy,ultrafast carrier dynamics,second harmonic generation
更新于2025-09-09 09:28:46