- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Flexible engineering of light emission in monolayer MoS <sub/>2</sub> via direct laser writing for multimode optical recording
摘要： Direct laser writing has been proved to be capable for effective modulation of optical and electrical properties of various nanomaterials. In this work, we designed a flexible direct laser writing approach to engineer photoluminescence (PL) properties of monolayer MoS2 and present its potential application in optical recording. PL spectra evolution of monolayer MoS2 under continuous-wave laser writing has been explored, where its PL energy can be precisely controlled by changing the writing time. This feature enables a multimode optical recording with spectral contrast in monolayer limit materials for high-capacity data storage technologies. Here, we constructed a proof-of-principle multimode optical recording on monolayer MoS2 based on the PL wavelength division multiplexing scheme and discussed the relevant challenges for practical applications. Our flexible approach with a mask-free feature and high spatial resolution is promising for applications in two-dimensional material-based information storage and optoelectronic devices.
关键词： direct laser writing,photoluminescence,monolayer MoS2,wavelength division multiplexing,optical recording
更新于2025-09-23 15:21:01
-
A new SERS substrate of self-assembled monolayer film of gold nanoparticles on silicon wafer for the rapid detection of polycyclic aromatic hydrocarbons
摘要： A facile and rapid method for the SERS detection of polycyclic aromatic hydrocarbons (PAHs) was reported. The Au colloids assemble to form gold nanoparticles (Au NPs) monolayer film at the air/water interface through the modification of n-dodecanethiol (DT), and then the film was directly transferred by tilt-lifting onto the silicon wafer to fabricate uniformed SERS substrate. PAHs could be preconcentrated into DT layer on the surface of the SERS substrate through the hydrophobic interaction, and detected by SERS. The linear range of detection for Benzo[a]-pyrene (B[a]P) is from 10-8 to 10-5 mol/L with a linearity (R2) of 0.92 to 0.99. The recovery rates range from 89.5% to 103.7%. The detection limit can reach the ng/L level. Pyrene (Pyr) and Chrysene (Chr) were also detected by SERS. The substrate had good stability, uniformity, reproducibility and reusability, which demonstrated that the DT-functionalized Au NPs film prepared by the self-assembly method at the air/water interface could be used as a reliable SERS candidate for the rapid analysis of PAHs.
关键词： self-assembled monolayer (SAM),air/water interface,SERS,polycyclic aromatic hydrocarbons (PAHs),gold nanoparticles (Au NPs)
更新于2025-09-23 15:21:01
-
[IEEE ESSDERC 2018 - 48th European Solid-State Device Research Conference (ESSDERC) - Dresden, Germany (2018.9.3-2018.9.6)] 2018 48th European Solid-State Device Research Conference (ESSDERC) - Gated Four-Probe Method to Evaluate the Impact of SAM Gate Dielectric on Mobility in MoS2 FET
摘要： This study reports the interfacial engineering by means of SAM (Self-assembled monolayer)-based gate dielectric on channel mobility in molybdenum disulfide (MoS2) field-effect transistors (FETs). A gated four-probe method was implemented to eliminate the effect of contact resistance on channel mobility. The formation of SAM significantly plays an important role in the improvement of channel mobility as high as 19 cm2/Vs in MoS2 FETs because the superior interfacial properties can be realized in MoS2/SAM structure. This study opens up interesting direction of interface engineering for research in the applications and developments of 2-dimensional materials-based thin film devices.
关键词： FETs,Interface properties,Channel mobility,Self-assembled monolayer,MoS2
更新于2025-09-23 15:21:01
-
Stability, spontaneous and induced polarization in monolayer MoC, WC, WS, and WSe
摘要： Using density functional theory based calculations, we design buckled honeycomb binary monolayer MoC, WC, WS, and WSe. The feasibility of their experimental synthesis is evident from their low formation energies, stable lattice vibrations, and high elastic stiffnesses. The difference in electronegativity of the building atoms and lack of inversion symmetry results in high spontaneous out-of-plane polarization whereas all the in-plane components cancel out. The existence of the mirror plane along the armchair direction vanishes the in-plane piezoelectric stress effects for a strain applied along the zigzag direction. However, a strain along the armchair direction on MoC and WC results in a high piezoelectric coefficient up to 10×10?10 C/m, about three times larger than that reported for monolayer MoS2. The polarization switching barriers for the out-of-plane components range from 0.55 to 2.70 eV per formula unit.
关键词： ferroelectricity,monolayer,density functional theory,polarization,piezoelectricity
更新于2025-09-23 15:21:01
-
Ultrafast Exciton Dissociation at the 2D-WS <sub/>2</sub> Monolayer/Perovskite Interface
摘要： In order for an excitonic photovoltaic (PV) device to perform efficiently, photogenerated excitons in the charge donor need to be dissociated through charge transfer (CT) to the acceptor rapidly after their photogeneration, and remain separated for a longer time to allow the collection of charges. To improve the efficiency of these steps, several combination of materials have been examined. Due to their excellent optical properties, two-dimensional transition metal dichalcogenides (2D-TMDs) have recently been explored. Another promising class of materials to platform efficient PVs is organic-inorganic perovskites. Here, we report on the ultrafast exciton dissociation through electron transfer from a 2D tungsten disulfide (WS2) monolayer to a thin layer of methylammonium lead iodide (CH3NH3PbI3) perovskites. Photoluminescence (PL) measurements showed that when the 2D-WS2 monolayer was covered with perovskites, its emission completely quenched, suggesting that the CT process is highly efficient. Despite that pump-probe spectroscopy measurements were carried out with a ~ 45 fs temporal resolution, the CT dynamics were not captured. A comparison of the ultrafast dynamics of the two band-edge excitons of the charge donor (2D-WS2) suggested that electron transfer is the dominant pathway of CT. Furthermore, these pump-probe measurements indicated that a small fraction of transferred electrons remained in the perovskites up to almost 2 ns. These findings may open a new horizon for understanding the dissociation of photogenerated excitons in 2D-TMD through hybridization with other class of nanomaterials.
关键词： Ultrafast Exciton Dissociation,Perovskite Interface,Hybrid Materials,Magnetic,Plasmonics,2D-WS2 Monolayer,Optical
更新于2025-09-23 15:21:01
-
Ultraviolet photodetectors using hollow p-CuO nanospheres/n-ZnO nanorods with a pn junction structure
摘要： We report on ultraviolet (UV) photodetectors with a pn junction structure consisting of hollow p-CuO (h-CuO) nanospheres and n-ZnO nanorods (NRs). To form the pn junction structure, thermal annealing was conducted using a transferred monolayer of Cu-ion-incorporated polymer spheres onto the n-ZnO NRs/n-Si substrate. Device performance was evaluated by comparing the effects of h-CuO nanosphere coverage changed by sphere shrinkage during thermal annealing of Cu-ion-incorporated polymer spheres. Three samples were prepared by varying the transfer times of h-CuO on ZnO NRs: 0 times (Reference), 1 time (CZ-I), and 2 times (CZ-II). The CZ-II-based UV detector shows a fast rising time of 1.8 s and a falling time of 0.26 s, which are faster rising by 2.2 and 1.3 times and faster falling by 3.1 and 32.6 times than those of the CZ-I and Reference UV detectors, respectively, under illumination with UV light at 254 nm. Moreover, the On/Off current ratio of the CZ-II UV detector is 4.58, which is about 3.3 times and 3.5 times higher than that of the CZ-I and Reference devices, respectively. The higher h-CuO coverage on the ZnO NRs that form the pn junction structure can effectively separate the electron and hole and suppress recombination by mutual transfer of photo-generated electrons and holes in the heterojunction.
关键词： Hollow CuO,ZnO,UV detector,transfer of spheres monolayer
更新于2025-09-23 15:19:57
-
Sensitive Detection of Dengue Virus Type 2 E-Proteins Signals Using Self-Assembled Monolayers/Reduced Graphene Oxide-PAMAM Dendrimer Thin Film-SPR Optical Sensor
摘要： In this work, sensitive detection of dengue virus type 2 E-proteins (DENV-2 E-proteins) was performed in the range of 0.08 pM to 0.5 pM. The successful DENV detection at very low concentration is a matter of concern for targeting the early detection after the onset of dengue symptoms. Here, we developed a SPR sensor based on self-assembled monolayer/reduced graphene oxide-polyamidoamine dendrimer (SAM/NH2rGO/PAMAM) thin film to detect DENV-2 E-proteins. Surface characterizations involving X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) confirms the incorporation of NH2rGO-PAMAM nanoparticles in the prepared sensor films. The specificity, sensitivity, binding affinity, and selectivity of the SPR sensor were then evaluated. Results indicated that the variation of the sensing layer due to different spin speed, time incubation, and concentration provided a better interaction between the analyte and sensing layer. The linear dependence of the SPR sensor showed good linearity (R2 = 0.92) with the lowest detection of 0.08 pM DENV-2 E-proteins. By using the Langmuir model, the equilibrium association constant was obtained at very high value of 6.6844 TM?1 (R2 = 0.99). High selectivity of the SPR sensor towards DENV-2 E-proteins was achieved in the presence of other competitors.
关键词： optical sensor,E-proteins,SPR sensor,PAMAM dendrimer,reduced graphene oxide,dengue virus,self-assembled monolayer
更新于2025-09-23 15:19:57
-
High-performance monolayer MoS2 photodetector enabled by oxide stress liner using scalable chemical vapor growth method
摘要： MoS2, as a typical representative of two-dimensional semiconductors, has been explored extensively in applications of optoelectronic devices because of its adjustable bandgap. However, to date, the performance of the fabricated photodetectors has been very sensitive to the surrounding environment owing to the large surface-to-volume ratio. In this work, we report on large-scale, high-performance monolayer MoS2 photodetectors covered with a 3-nm Al2O3 layer grown by atomic layer deposition. In comparison with the device without the Al2O3 stress liner, both the photocurrent and responsivity are improved by over 10 times under 460-nm light illumination, which is due to the tensile strain induced by the Al2O3 layer. Further characterization demonstrated state-of-the-art performance of the device with a responsivity of 16.103 A W?1, gain of 191.80, NEP of 7.96?×?10?15 W Hz?1/2, and detectivity of 2.73?×?1010 Jones. Meanwhile, the response rise time of the photodetector also reduced greatly because of the increased electron mobility and reduced surface defects due to the Al2O3 stress liner. Our results demonstrate the potential application of large-scale strained monolayer MoS2 photodetectors in next-generation imaging systems.
关键词： photodetector,Al2O3,stress liner,monolayer MoS2
更新于2025-09-23 15:19:57
-
Interplay of charge transfer and disorder in optoelectronic response in Graphene/hBN/MoS<sub>2</sub> van der Waals heterostructures
摘要： Strong optoelectronic response in the binary van der Waals heterostructures of graphene and transition metal dichalcogenides (TMDCs) is an emerging route towards high-sensitivity light sensing. While the high sensitivity is an effect of photogating of graphene due to inter-layer transfer of photo-excited carriers, the impact of intrinisic defects, such as traps and mid-gap states in the chalcogen layer remain largely unexplored. Here we employ graphene/hBN (hexagonal boron nitride)/MoS2 (molybdenum disulphide) trilayer heterostructures to explore the photogating mechanism, where the hBN layer acts as interfacial barrier to tune the charge transfer timescale. We find two new features in the photoresponse: First, an unexpected positive component in photoconductance upon illumination at short times that preceeds the conventional negative photoconductance due to charge transfer, and second, a strong negative photoresponse at infrared wavelengths (up to 1720 nm) well-below the band gap of single layer MoS2. Detailed time and gate voltage-dependence of the photoconductance indicates optically-driven charging of trap states as possible origin of these observations. The responsivity of the trilayer structure in the infrared regime was found to be extremely large (> 108 A/W at 1550 nm using 20 mV source drain bias at 180 K temperature and ≈ ?30 V back gate voltage). Our experiment demonstrates that interface engineering in the optically sensitive van der Waals heterostructures may cast crucial insight onto both inter- and intra-layer charge reorganization processes in graphene/TMDC heterostructures.
关键词： defects and disorders in TMDCs,monolayer MoS2,phototransistor,graphene,infrared photodetection,Van der Waals heterostructures
更新于2025-09-23 15:19:57
-
Largea??Scale Ultrathin 2D Widea??Bandgap BiOBr Nanoflakes for Gatea??Controlled Deepa??Ultraviolet Phototransistors
摘要： Ternary two-dimensional (2D) semiconductors with controllable wide bandgap, high ultraviolet (UV) absorption coefficient, and critical tuning freedom degree of stoichiometry variation have a great application prospect for UV detection. However, as-reported ternary 2D semiconductors often possess a bandgap below 3.0 eV, which must be further enlarged to achieve comprehensively improved UV, especially deep-UV (DUV), detection capacity. Herein, sub-one-unit-cell 2D monolayer BiOBr nanoflakes (≈0.57 nm) with a large size of 70 μm are synthesized for high-performance DUV detection due to the large bandgap of 3.69 eV. Phototransistors based on the 2D ultrathin BiOBr nanoflakes deliver remarkable DUV detection performance including ultrahigh photoresponsivity (Rλ, 12739.13 A W?1), ultrahigh external quantum efficiency (EQE, 6.46 × 106%), and excellent detectivity (D*, 8.37 × 1012 Jones) at 245 nm with a gate voltage (Vg) of 35 V attributed to the photogating effects. The ultrafast response (τrise = 102 μs) can be achieved by utilizing photoconduction effects at Vg of ?40 V. The combination of photocurrent generation mechanisms for BiOBr-based phototransistors controlled by Vg can pave a way for designing novel 2D optoelectronic materials to achieve optimal device performance.
关键词： monolayer BiOBr,deep UV phototransistors,wide-bandgap semiconductors,high gain
更新于2025-09-23 15:19:57