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Graphene/HgTe Quantum-Dot Photodetectors with Gate-Tunable Infrared Response
摘要： Graphene-based vertical heterostructures are of interest as emerging electronic and optoelectronic devices. Here, we report the study of photovoltaic response from graphene/HgTe quantum-dot junction. The graphene/HgTe quantum-dot junction combines the high carrier mobility of graphene and tunable infrared optical absorption of HgTe colloidal quantum dots, which offers promising route for the next-generation infrared optoelectronics. We demonstrate that both the sign and magnitude of the short-circuit photocurrents and open-circuit voltages can be controlled by the applied gate voltage, which tunes the Fermi level and the interfacial built-in potential across the junction. The interfacial energy band diagram is deduced to provide the fundamental understanding of the essential physics behind the graphene/quantum-dot film junction.
关键词： graphene/HgTe CQDs junction,photovoltaic detection,interfacial photocarrier transport,gate-tunable photoresponse,infrared
更新于2025-09-19 17:13:59
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Enhanced photoresponse and surface charge transfer mechanism of graphene-tungsten disulfide heterojunction
摘要： Two dimensional (2D) materials based heterostructures have gained profound interest in optoelectronics and electronic technology due to additional functionalities over the individual structures. This study demonstrates the fabrication and characterization of van der Waal heterostructure by selective coverage of graphene (Gr) with tungsten disulfide (WS2). The electrical transport measurements divulge the tweaking of charge carriers in graphene after WS2 coverage. Such architecture provides route towards the formation of heterojunction within graphene FET based on surface charge transfer between Gr/WS2 heterointerface. Furthermore, the exposure of device towards deep ultraviolet light (DUV) enhances the charge transfer mechanism and as a result more pronounced junction is observed. The photoelectrical characterization of heterostructure is also investigated by calculating detectivity (D*), external quantum efficiency (EQE) photoresponsivity (Rλ). Our results suggest that 2D heterostructures in combination with DUV irradiations are more efficient and suitable choice to selectively tune the properties of 2D material-based optoelectronic devices.
关键词： p-n junction,Tungsten disulfide,Graphene,Photoresponse,Deep ultraviolet light (DUV),Heterostructure
更新于2025-09-19 17:13:59
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Exploring conduction mechanism and photoresponse in <i>P-</i> GaN <i>/n-</i> MoS <sub/>2</sub> heterojunction diode
摘要： Mixed-dimensional heterostructures have shown their potential in electronic devices. However, their functionality is limited by a complete understanding of the contacts and the current transport behavior. Here, we explore the electrical properties of the P-n heterojunction diode fabricated using p-type gallium nitride and layered molybdenum disulfide. The resulting P-n diode is rectifying in nature with current rectification of three orders of magnitude. The careful choice of Ohmic contacts on both the semiconductors reveals distinctly rectifying behavior of the heterojunction diode. The as-fabricated diode is tested at various temperatures, and the conduction mechanism in the device is analyzed based on the temperature dependent electrical characterizations. In addition, photoresponse characterization reveals that the P-n heterojunction is highly sensitive to a 405 nm laser with a high responsivity of 444 A/W at a reverse bias voltage of 5 V and shows photovoltaic behavior. The heterojunction diode acts as a self-powered photodetector. Our findings show the potential of the MoS2/GaN heterojunction in highly efficient photodetector applications.
关键词： conduction mechanism,heterojunction diode,photoresponse,P-GaN,n-MoS2
更新于2025-09-19 17:13:59
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Laser annealing towards high-performance monolayer MoS2 and WSe2 field effect transistors
摘要： The transition metal dichalcogenides (TMDCs) have been intensively investigated as one of promising nanoelectronic and optoelectronic materials. However, the pervasive adsorbates on the surface of monolayer TMDCs, including oxygen and water molecules from the ambient environments, predominately degrade the device performance, thus hindering the precise applications. In this work, we report the effect of laser irradiation on the transport and photoresponse of monolayer MoS2 and WSe2 devices, and this laser annealing process is demonstrated as one straightforward approach to remove the physically adsorbed contaminations. Compared with vacuum pumping and in-situ thermal annealing treatments, the field-effect transistors after the laser annealing show more than one order of magnitude higher on-state current, and no apparent degradation of device performance at low temperature. The mobility of monolayer WSe2 devices can be enhanced by 3-4 times, and for single-layered MoS2 devices with the commonly used SiO2 as the back-gate, the mobility increases by 20 times, reaching 37 cm2 ? V?1 ? s?1. The efficient cleaning effect of the laser annealing is also supported by the reduction of channel and contact resistances revealed by the transmission line experiment. Further, the enhanced photocurrent by a factor of 10 has been obtained in the laser annealed device. These findings pave the way for the high-performance monolayer TMDCs-based electronic and optoelectronic devices with the clean surface and intrinsic properties.
关键词： TMDCs,monolayer MoS2,photoresponse,field-effect transistors,laser annealing,monolayer WSe2
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 2nd British and Irish Conference on Optics and Photonics (BICOP) - London, United Kingdom (2019.12.11-2019.12.13)] 2019 IEEE 2nd British and Irish Conference on Optics and Photonics (BICOP) - Oligofluorene Truxene Laser Sensor: Towards Bacteria Growth Detection
摘要： We demonstrate the performance enhancement of field-effect transistor (FET)-based plasmonic terahertz (THz) detector with monolithic integrated antenna in low-impedance regime and report the experimental results of Si MOSFET impedance in THz regime using 0.2-THz measurement system. By designing FET with low-impedance ranges (<1 kΩ) and integrating antennas with impedances of 50 and 100 Ω, we found that our low-impedance MOSFETs have the input impedance criterion of 50 Ω at 0.2 THz and the MOSFETs with thinner gate oxide show the highly enhanced plasmonic photoresponses at 50-Ω antenna by 325 times from the result of the detector without antenna.
关键词： impedance,plasmonic,detector,photoresponse,MOSFET,terahertz
更新于2025-09-19 17:13:59
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Effect of Si substrate modification on improving the crystalline quality, optical and electrical properties of thermally-evaporated BaSi2 thin-films for solar cell applications
摘要： We have grown orthorhombic barium disilicide (BaSi2) thin-films on modified silicon (Si) substrates by a thermal evaporation method. The surface modification of Si substrate was performed by a metal-assisted chemical etching method. The effects of etching time te on crystalline quality as well as optical and electrical properties of the BaSi2 films were investigated. The obtained results showed that substrate modification can enhance the crystalline quality and electrical properties; reduce the light reflection; and increase the absorption of the BaSi2 thin-films. The te of 8 s was chosen as the optimized condition for surface modification of Si substrate. The achieved inferred short-circuit current density, Hall mobility, and minority carrier lifetime of the BaSi2 film at te of 8 s were 38 mA/cm2, 273 cm2/Vs, and 2.3 μs, respectively. These results confirm that the BaSi2 thin-film evaporated on the modified Si substrate is a promising absorber for thin-film solar cell applications.
关键词： hall mobility,substrate modification,photoresponse,silicide semiconductor,Barium disilicide,minority carrier lifetime,optical property,thermal evaporation
更新于2025-09-19 17:13:59
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Enhanced photoresponse characteristics of ZnO polymer nanocomposite: effect of variation of surface density of nanocrystals
摘要： Zinc oxide (40–100 nm size) nanocrystals were successfully grown on the surface of an organic polymer (cellulose) by a low-cost solution casting method. Zinc precursor (zinc nitrate hexahydrate) concentration was varied from 25–75 mM, to synthesize several sets of ZnO-cellulose nanocomposite (ZCNC). The morphology and size of the nanocrystals were studied by a field emission scanning electron microscope and due to variation in the precursor concentration, a significant change in the surface density of the nanocrystals was observed. The maximum surface density was perceived at a precursor concentration of 50 mM. The Brunauer–Emmett–Teller (BET) surface areas of the ZCNCs were estimated by the nitrogen adsorption–desorption method, and a maximum surface area of 2.861 m2/g was observed. The structure, as well as composition of the nanocomposite, were studied by X-ray diffraction and energy dispersive X-rays analysis, respectively. The electrical properties of the composite were studied by current–voltage measurement while the photoresponse was recorded by time resolve photocurrent measurement. The photocurrent of the ZCNC sensor device increased from 6.783 × 10?8 to 4.91 × 10?6 A under UV illumination. The UV response (IUV/IDark) and sensitivity of the device were 72.38 and 7138, respectively. Also, the photocurrent rise time and decay time were 8 s and 9 s, respectively. The enhanced photoresponse with short response time observed for the ZnO-cellulose nanocomposite may lead to the fabrication of inexpensive ultraviolet sensors.
关键词： photoresponse,cellulose,nanocomposite,UV sensor,ZnO
更新于2025-09-19 17:13:59
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CsPbBr <sub/>3</sub> Quantum Dots as Artificial Antennas to Enhance the Light-Harvesting Efficiency and Photoresponse of Zinc Porphyrin
摘要： Broadening the spectral range and enhancing the efficiency of light-harvesting materials are important to the design of novel optoelectronic devices. In this work, CsPbBr3 quantum dots (QDs) are introduced as artificial antennas to enhance both the light-harvesting efficiency and photoresponse of zinc porphyrin (ZnP). The Fluorescence Resonance Energy Transfer (FRET) process both in solution and films from the donor CsPbBr3 QD to the acceptor ZnP have been systematically investigated, and an energy transfer efficiency over 70% in solution and a high optical sensitivity have been realized with the optimal of QD/ZnP ratio on films. A photocurrent density of up to 1.00×10-4 A·cm-2 can be achieved for the QD/ZnP film, and the corresponding on/off photocurrent value can be increased by two orders of magnitude compared with that of ZnP. Furthermore, the as-prepared light-harvesting film also demonstrates a high optical sensitivity at the optimal QD/ZnP ratio. Our research provides an effective way for designing and improving the QD/ZnP “antenna” for solar-energy harvesting devices.
关键词： Zinc Porphyrin,CsPbBr3 Quantum Dots,FRET,Photoresponse,Light-Harvesting Efficiency
更新于2025-09-19 17:13:59
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The transparent Schottky junction of reduced graphene oxide/SnO <sub/>2</sub> nanoarrays towards enhanced broadband photoresponse
摘要： The rGO/SnO2 nanoarrays (rGO/SnO2 NAs) Schottky junction is synthesized by a series of RF magnetron sputtering, hydrothermal and electrochemical deposition. The unique transparent junction exhibits the broadband photoelectric responses from the ultraviolet to visible light. As shown, the proper rGO/SnO2 NAs display highly transparency of about ~60% and dramatically enhance photoelectric conversion of about ~100 times than that of the initial Schottky junction. Finally, the mechanism of the Schottky junction is investigated.
关键词： reduced graphene oxide,broadband photoresponse,transparent Schottky junction,SnO2 nanoarrays
更新于2025-09-16 10:30:52
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SYNTHESIS AND CHARACTERIZATION OF La-DOPED ZnO (La:ZnO) FILMS FOR PHOTODETECTORS
摘要： In this work, the La-doped ZnO thin films were fabricated with different La concentrations by the use of sol–gel technique to synthesize the photodevice. The transparent metal oxide La-doped ZnO thin films were grown on glass and p-Si substrates using spin coating technique. Optical, surface morphology and electrical characterization of the fabricated Al/p-Si/La:ZnO/Al devices have been performed using I–V and C/G–V characteristics under dark and different illumination conditions. Herein, from I–V characteristics, the crucial electronic parameters such as barrier height, ideality factor and series resistance were investigated. The photodevice transient photocurrent increases with the increase of illumination intensity. The current ratios of Ion/Ioff were calculated for the fabricated devices. Among the devices, the highest photoresponse was found to be about 2186 for the Al/p-Si/La(0.5 wt.%):ZnO/Al structure. The Rs–V behavior of fabricated device confirms the presence of interface states. The obtained results and photoresponse behaviors suggested that Al/p-Si/La:ZnO/Al devices can enhance the applications in optoelectronic devices such as photodetectors.
关键词： sol–gel,photoresponse,photodetector,doped ZnO,Electrical characteristics
更新于2025-09-16 10:30:52