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[IEEE 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Bengaluru, India (2018.12.17-2018.12.19)] 2018 4th IEEE International Conference on Emerging Electronics (ICEE) - Impact of post deposition annealing of ZrO <sub/>2</sub> insulating layer on the performance of GaN metal-semiconductor-metal ultraviolet photodetectors
摘要： GaN metal–semiconductor–metal (MSM) ultraviolet photodetectors without and with annealed ZrO2 insulating layers are successfully fabricated. It is found that the dark current is reduced by 3 times post annealing of the oxide layer. GaN MSM photodetectors exhibit large internal gain which can be explained by considering the presence of hole traps in oxide layer. Further, reduction in gain and increase in transient response time of photodetectors post annealing of ZrO2 layer reveal that the density of shallow trap states is considerably reduced by the annealing step. It is noticed that though the response of all the states is affected by the annealing but the fast component of photoresponse is rather severely hampered. The present investigations clearly demonstrate that reduction of dark current is not the sole criteria for improving the performance of a photodetector. Rather, transient response of the device and hence the band width of the device along with the leakage current and gain should be taken into the consideration for qualifying the overall performance of the photodetectors.
关键词： Photoresponse,GaN,Schottky diodes,Responsivity,I-V
更新于2025-09-16 10:30:52
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Directed self-assembly of viologen-based 2D semiconductors with intrinsic UVa??SWIR photoresponse after photo/thermo activation
摘要： Extending photoresponse ranges of semiconductors to the entire ultraviolet–visible (UV)–shortwave near-infrared (SWIR) region (ca. 200–3000 nm) is highly desirable to reduce complexity and cost of photodetectors or to promote power conversion efficiency of solar cells. The observed up limit of photoresponse for organic-based semiconductors is about 1800 nm, far from covering the UV–SWIR region. Here we develop a cyanide-bridged layer-directed intercalation approach and obtain a series of two viologen-based 2D semiconductors with multispectral photoresponse. redox-active N-methyl bipyridinium cations with near-planar structures are sandwiched by cyanide-bridged MnII–FeIII or ZnII–FeIII layers. Radical–π interactions among the infinitely π-stacked N-methyl bipyridinium components favor the extension of absorption range. Both semiconductors show light/thermo-induced color change with the formation of stable radicals. They have intrinsic photocurrent response in the range of at least 355–2400 nm, which exceeds all reported values for known single-component organic-based semiconductors.
关键词： photoresponse,viologen-based,semiconductors,UV–SWIR,2D materials
更新于2025-09-16 10:30:52
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GaSe/MoS <sub/>2</sub> Heterostructure with Ohmica??Contact Electrodes for Fast, Broadband Photoresponse, and Selfa??Driven Photodetectors
摘要： In this letter, the vertically-stacked GaSe/MoS2 heterostructures with indium tin oxide (ITO) and Ni/Au as contact electrodes are successfully fabricated, respectively. The GaSe/MoS2 heterostructure exhibits a broadband photoresponse covering the range of visible to near-infrared spectra at room temperature without external bias voltage. When ITO serves as contact electrodes, a high rectification ratio, i.e., 1.5 × 104 at VDS = ±1 V, and an excellent photoelectric performance, i.e., responsivity of ≈0.67 A W-1, specific detectivity of ≈2.3 × 1011 cm Hz1/2 W-1 and external quantum efficiency of ≈160% at the wavelength of 520 nm is achieved. Moreover, the GaSe/MoS2 heterostructure with Ohmic-contact ITO electrodes demonstrates a faster response time of 155 μs, which is 4 times faster than the GaSe/MoS2 heterostructure with Ni/Au electrodes and about 300 times faster than previous reports. These results reveal the presence of an abrupt p–n junction between GaSe and MoS2 and significant role of electrode-contact mode in determining the photoelectric properties of GaSe/MoS2 heterostructure.
关键词： photoresponse,GaSe/MoS2 heterostructure,self-driven photodetector,Ohmic-contact
更新于2025-09-16 10:30:52
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Fast and broadband photoresponse of few-layer GeSe field-effect transistor with direct bandgaps
摘要： Few-to-monolayer germanium selenide, a new Ⅳ-Ⅵ group layered material recently fabricated by mechanical exfoliation and subsequent laser thinning, is promising in very fast and broadband optoelectronic applications for its excellent stability, natural p-type semiconductor, complicated band structures, and inert surface properties. However, large-scale production of such few-layer GeSe devices with superior performance is still in early stages. In this study, field-effect transistors (FETs) made of few-layer GeSe with direct bandgaps are fabricated. Transistor performance with Schottky contact characteristics is measured at room temperature. Field effect mobility of 4 cm2/Vs and drain currents modulated both in hole and electrons are measured. Photoresponse as a function of the illumination wavelength, power, and frequency are characterized. The few-layer GeSe transistor shows photoresponse to the illumination wavelengths from the visible up to 1400 nm, and photoresponse rise (fall) time of 13 μs (19 μs), demonstrating very broadband and fast detection. The ambipolar behavior and the photoresponse characteristics demonstrate great potential of few-layer GeSe for applications in high stability, very fast and broadband of optoelectronic devices.
关键词： broadband photoresponse,photoresponse time,ambipolar behavior,field effect transistors,direct bandgaps,few-layer GeSe
更新于2025-09-12 10:27:22
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Tunable Photoresponse by Gate Modulation in Bilayer Graphene Nanoribbon Devices
摘要： Control of absorption and photocurrent conversion is of practical importance for the design of photoelectric devices. In this paper, using simulations, we demonstrate that the photoresponse of a bilayer graphene nanoribbon (GNR) device can be controlled by gate voltage modulation. A vertical gate ?eld shifts the potential on the top and bottom layers in opposite directions, resulting in a continuous change of band gap with applied gate voltage. This ?eld simultaneously facilitates separation of photoexcited electron?hole pairs and gives rise to a photocurrent in a selected photon energy range. The photoresponse of a bilayer GNR device can thus be tuned by adjusting the applied gate voltage. In addition, the light frequency range can be changed by using nanoribbons of di?erent widths. These ?ndings provide a basis for the design of adjustable optoelectronic devices using two-dimensional materials.
关键词： optoelectronic devices,gate modulation,graphene nanoribbon,two-dimensional materials,photoresponse
更新于2025-09-12 10:27:22
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Self-catalyzed growth of GaSb nanowires for high performance ultraviolet-visible-near infrared photodetectors; 自催化生长GaSb纳米线及其在高性能紫外-可见-近红外光电探测器中的应用;
摘要： A simple self-catalyzed chemical vapor deposition process was conducted to synthesize single-crystalline GaSb nanowires, where Ga droplets were utilized as the catalysts. The as-grown GaSb nanowires exhibited typical p-type semiconductor behavior with the calculated hole mobility of about 0.042 cm2 V?1 s?1. The photoresponse properties of the GaSb nanowires were studied by fabricating nanowire photodetectors on both rigid and flexible substrates. The results revealed that the photodetectors exhibited broad spectral response ranging from ultraviolet, visible, to near-infrared region. For the device on rigid substrate, the corresponding responsivity and the detectivity were calculated to be 3.86×103 A W?1 and 3.15×1013 Jones for 500 nm light, and 7.22×102 A W?1 and 5.90×1012 Jones for 808 nm light, respectively, which were the highest value compared with those of other reported Ga1?xInxAsySb1?y structure nanowires. Besides, the flexible photodetectors not only maintained the comparable good photoresponse properties as the rigid one, but also possessed excellent mechanical flexibility and stability. This study could facilitate the understanding on the fundamental characteristics of self-catalyzed grown GaSb nanowires and the design of functional nano-optoelectronic devices based on Gasb nanowires.
关键词： photoresponse,GaSb nanowires,chemical vapor deposition,mobility,near-infrared,flexible
更新于2025-09-12 10:27:22
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A Lattice-mismatched PbTe/ZnTe Heterostructure with High-speed Mid-infrared Photoresponses
摘要： In this work, a novel heterostructure consisting of di?erent lattice structures with zincblende ZnTe and rock-salt PbTe is proposed. The PbTe/ZnTe heterostructures are grown by molecular beam epitaxy. Type-I band alignment at the PbTe/ZnTe heterointerface is revealed by X-ray photoelectron spectroscopy. The interface of the heterostructure exhibits exotic electrical properties. The novel heterostructure is then implemented to develop high-performance mid-infrared photodetectors which demonstrate pronounced responsivity, swift response speed and high detectivity. The new photodetectors utilize the lateral photovoltaic e?ect which facilitates the understanding of the novel PbTe/ZnTe heterostructures.
关键词： mid-infrared detectors,fast photoresponse,lead telluride,lateral photovoltaic e?ect,semiconductor heterostructures
更新于2025-09-12 10:27:22
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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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Theoretical correlation and effect of annealing on the photoresponse of vertically strain-coupled In <sub/>0.5</sub> Ga <sub/>0.5</sub> As/GaAs quantum dot heterostructures
摘要： Here, we propose a di?erent approach for growing strain-coupled In0.5Ga0.5As quantum dot infrared photodetectors (QDIPs) with varying dot layer periodicity. Strain calculation is done throughout the quantum dot (QD) heterostructures, which has a signi?cant e?ect on the carrier probability density functions. The localization of the electron probability density function in each heterostructure has a strong correlation with the photoresponse. The con?ned electron wavefunction in the top QD layer of the optimized device heterostructure (trilayer QDIP having dot layer periodicity of three) would be useful for hyperspectral imaging applications owing to its narrow (8.67 meV) photoresponse. Rapid thermal annealing treatment was carried out on the trilayer QDIP to investigate the enhancement in its optoelectronic properties. The dark current density reduced by two orders, and the operating temperature increased by 30 °C for the 650 °C-annealed counterpart. Also, the responsivity enhanced by two times (2.05 A/W at ?1 V) for the annealed QDIP.
关键词： In0.5Ga0.5As,rapid thermal annealing,photoresponse,strain-coupled,quantum dot infrared photodetectors
更新于2025-09-12 10:27:22
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Enhanced Photoresponse of Indium-Doped Tin Disulfide Nanosheets
摘要： Doping of tin disulfide (SnS2) is an effective strategy to regulate its physical and chemical properties. In this work, In doping was used to manipulate the photoresponse behavior of SnS2-based photodetectors. In-doped SnS2 nanosheets were synthesized via a facile hydrothermal method. It was found that the In doping concentration plays an important role in the size of the fabricated SnS2 nanosheets. With the increase in the In doping concentration, the lateral size of samples increased from ~210 to ~420 nm, but the crystallinity became poor at higher concentrations. EDX-mapping results show that the In was homogeneously distributed in the samples. In addition, a redshift was observed in the binding energy of Sn and S with the increased In doping concentration, which may be due to the p-type doping of In in SnS2. After In doping, the performance of SnS2-based photodetectors was significantly improved. The photoresponse speed of In-doped SnS2-based photodetectors was faster than pristine SnS2-based devices under the illumination of 532 and 405-nm lasers. This work develops an effective approach of In doping to enhance the photoresponse characteristics of SnS2-based photodetectors, and proves that In-doped SnS2 has vast potential in optoelectronic applications.
关键词： photoresponse characteristics,Doping,Tin disulfide,photodetector,Layered metal dichalcogenides
更新于2025-09-12 10:27:22