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Correlation between the morphology and the opto-electronic and electrical properties of organometallic halide perovskite (CH<sub>3</sub>NH<sub>3</sub>MH<sub>3</sub>) thin films
摘要： Organometallic halide perovskites are emerging as a promising class of materials for optoelectronic applications. Crystal morphology is important for improving the organic-inorganic lead halide perovskite semiconductor property in optoelectronic, electrical and photovoltaic devices. It is thus important to investigate how the changes in crystal morphology affect the semiconductor behavior. This work presents a study that was carried out to assess the relationship between different deposition methodologies and the opto-electronic and electrical properties of the resultant organometallic halide perovskite thin films. Herein, single step solution deposition method and two step solution deposition methods have been used to deposit perovskite thin films. The structure and morphology of perovskite was controlled by changing concentration, annealing temperatures and dip coating times. From the study, prepared films showed different morphologies as the concentration, annealing temperatures and dip coating times were varied. Optical band gap energies of 2.23 eV, 2.13 eV and 2.09 eV were obtained for samples prepared by single step solution deposition method and 1.57 eV, 1.55 eV and 1.52 eV for two step solution deposition method. The sheet resistance values decreased with an increase in concentration, annealing temperatures and dip coating times. The decrease in optical band gap energy and sheet resistances are excellent properties for high performance photovoltaic devices.
关键词： Perovskite,sheet resistivity,activation energy,band gap,sheet resistance,spectroscopy
更新于2025-11-19 16:56:35
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Effect of front TCO on the performance of rear-junction silicon heterojunction solar cells: Insights from simulations and experiments
摘要： In this study we make a detailed comparison between indium tin oxide (ITO), aluminum-doped zinc oxide (ZnO:Al) and hydrogenated indium oxide (IO:H) when applied on the illuminated side of rear-junction silicon heterojunction (SHJ) solar cells. ITO being the state of the art material for this application, ZnO:Al being an attractive substitute due to its cost effectiveness and IO:H being a transparent conductive oxide (TCO) with high-mobility and excellent optical properties. Through numerical simulations, the optically optimal thicknesses for a double layer anti-reflective coating system, consisting of the respective TCO and amorphous silicon oxide (a-SiO2) capping layers are defined. Through two-dimensional electrical simulations, we present a comparison between front-junction and rear-junction devices to show the behavior of series resistance (Rs) in dependence of the TCO sheet resistance (Rsh) and the device effective lifetime (τeff). The study indicates that there is a τeff dependent critical TCO Rsh value, above which, the rear-junction device will become advantageous over the front-junction design in terms of Rs. Solar cells with the respective layers are analyzed. We show that a thinner TCO optimized layer will result in a benefit in cell performance when implementing a double layer anti-reflective coating. We conclude that for a highest efficiency solar cell performance, a high mobility TCO, like IO:H, is required as the device simulations show. However, the rear-junction solar cell design permits the implementation of a lower conductive TCO in the example of the cost-effective ZnO:Al with comparable performance to the ITO, opening the possibility for substitution in mass production.
关键词： Transparent conductive oxide,Sheet resistance,Series resistance,Rear-junction,Silicon heterojunction,Anti-reflective coating
更新于2025-10-22 19:40:53
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Effect of O <sub/>2</sub> Flow Rate on Properties of Mn–SnO <sub/>2</sub> /Ag/Mn–SnO <sub/>2</sub> Multilayer Film
摘要： Multilayer films with Mn–SnO2 (MTO)/Ag/Mn–SnO2 (MTO) hybrid structure were prepared on a flexible polyethylene terephthalate (PET) substrate using a DC/RF sputtering system at room temperature. The optical, electrical, and structural properties of the thus-synthesized multilayer films were systematically investigated as a function of the O2/(Ar + O2) flow rate. The transmittance of the MTO/Ag/MTO multilayer films at 550 nm increased gradually from 83.1% to 87.9% and the sheet resistance (Rs) of the multilayer films increased from 6.3 to 9.8 Ω/sq upon increasing the O2/(Ar + O2) flow rate. The highest figure of merit (ΦTC) of the MTO/Ag/MTO multilayer film was 45.7 × 10?3 Ω?1 at an O2/(Ar + O2) flow rate of 2.8%. X-ray photoelectron spectra of multilayer films obtained with different O2/(Ar + O2) flow rates showed no noticeable variation.
关键词： Sheet Resistance,Figure of Merit,Transmittance,Gas Mixture Rate,Oxide/Metal/Oxide Structure
更新于2025-09-23 15:23:52
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Silver Nanowires Inks for Flexible Circuit on Photographic Paper Substrate
摘要： Silver nanowires (AgNWs) have inspired many research interests due to their better properties in optical, electric, and flexible applications. One such exploitable use is as the electrical conductive fillers for print electronics. In this paper, AgNWs with mean a diameter of 80 nm and mean length of 13.49 μm were synthesized using the polyol solvothermal method. A sonication-induced scission process was used to obtain AgNWs with a length range of 7.64–11.21 μm. Further AgNWs inks were prepared with the as-synthesized AgNWs as conductive fillers in anhydrous ethanol. The conductive inks were coated on resin coated photographic paper substrate using the knife coating process and dried at room temperature. The effects of the number of layers of AgNWs coating, the concentration of AgNWs, and the length of AgNWs on the microstructure and electrical properties of samples were investigated by scanning electron microscopy and using the four-point probe method. The results show that the conductivity of the AgNWs coating increases with the increase in the number of layers in the AgNWs coating, concentration and length of the AgNWs.
关键词： sheet resistance,silver nanowires inks,flexible circuit,photographic paper
更新于2025-09-23 15:22:29
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Electrical characterization of single nanometer-wide Si fins in dense arrays
摘要： This paper demonstrates the development of a methodology using the micro four-point probe (μ4PP) technique to electrically characterize single nanometer-wide fins arranged in dense arrays. We show that through the concept of carefully controlling the electrical contact formation process, the electrical measurement can be confined to one individual fin although the used measurement electrodes physically contact more than one fin. We demonstrate that we can precisely measure the resistance of individual ca. 20 nm wide fins and that we can correlate the measured variations in fin resistance with variations in their nanometric width. Due to the demonstrated high precision of the technique, this opens the prospect for the use of μ4PP in electrical critical dimension metrology.
关键词： micro four-point probe,electrical characterization,finFET,sheet resistance,critical dimension metrology
更新于2025-09-23 15:22:29
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Laser-induced growth of large-area epitaxial graphene with low sheet resistance on 4H-SiC(0001)
摘要： Multilayer graphene on SiC is a promising material due to its compatibility with modern electronics technology. Herein, we demonstrate the growth of large-area (~10 × 5 mm2), high-quality (D/G area ratio: ~0.03) epitaxial graphene on 4H-SiC(0001) using a high-power continuous laser with an extremely fast heating rate of 500 °C/s. As the growth temperature rises from 1550 °C to 1780 °C, the number of graphene layers increases from three to more than ten. The obtained graphene/SiC samples are highly conductive, with a sheet resistance of as low as ~0.43 Ω/sq. The high power and fast heating rate of the laser contribute to the formation of large-area and low-sheet-resistance graphene. The high conductivity makes graphene/SiC a very promising material for applications in conductive films. The growth mechanism of graphene and the influence of the structural properties of graphene on the conductivity are also discussed.
关键词： Sheet resistance,Large-area,4H-SiC,Continuous laser,Epitaxial graphene
更新于2025-09-23 15:21:01
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Strong Quantum Confinement Effects in Nanometer Devices with Graphene Directly Grown on Insulator by Catalyst-free Chemical Vapor Deposition
摘要： Background: The understanding of electrical properties of defective graphene in nanometer regime has lagged behind. Objective: This report intends to characterize defective but practically useful graphene as nanometer devices. Method: A-few-layer-thick graphene was directly grown on SiO2 substrate by alcohol-chemical vapor deposition (alcohol-CVD) using ethanol as carbon source and without the use of any catalytic metal. The graphene film was delineated into nanometer structures by electron beam lithography to make the nanoscale devices. Results: The Raman spectra of the graphene sheet on SiO2 shows relatively large D peak, which means the graphene is defective and consists of nanograins with an estimated size of 17 nm. Modulation of the graphene resistance by the gate voltage Vg was studied at room temperature. The film shows only p-type conduction, with a sheet resistance of 3.7 kΩ/□ and field-effect mobility calculated to be 44 cm2/Vs. From the temperature dependence of the graphene sheet, it is found that the resistance increases only by 7% from room temperature to 10 K, indicating low potential barrier between the domains, even though the graphene film is as thin as 1.6 nm and defective. From the conductance (Id/Vd) contour plot measured at 10 K of these nanodevices, aperiodic Coulomb-blockade feature and transport with a large gap were observed. Conclusion: Correlation among narrowest constriction widths, the variation of the addition energies and transport gaps in disordered graphene nanostructures is evident. These graphene nanodevices may have promising application in various nanodevices like single-electron (or single-hole) transistor, single-molecule transistor, van-der-Waals stacked nanodevices, etc.
关键词： graphene nanometer devices,Graphene nanostructures,sheet resistance,Raman spectra,Coulomb blockade,alcohol chemical vapor deposition,electron beam lithography
更新于2025-09-23 15:21:01
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Study and Calculation Electrical Properties of Silver Thin Layers by Four- Point Probe Method
摘要： In this research Ag thin layers on silicon p-type substrate with crystal orientation (100) and 300, 360 and 400 nm thicknesses by thermal evaporation was deposited. Four-point probe and XRD analysis of surface layers consequently for study electrical properties included of sheet resistance, conductivity, resistivity and investigation of Ag phase formed, was done. As result XRD was shown that at 400 nm the best state of silver face-central cubic (FCC) structure with crystal orientation (200) was formed and by Deby-Scherrer formula distance between successive plates was calculated 8.94 nm. Four-point illustrated that sheet resistance and electrical resistivity with increase thickness, decreases while conductance increases. At 400 nm thickness Ag layer has the most conductivity and the lowest resistance.
关键词： FCC lattice,Thickness,Sheet Resistance,Conductivity
更新于2025-09-23 15:21:01
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Pulsed-grown graphene for flexible transparent conductors
摘要： In the race to find novel transparent conductors for next-generation optoelectronic devices, graphene is supposed to be one of the leading candidates, as it has the potential to satisfy all future requirements. However, the use of graphene as a truly transparent conductor remains a great challenge because its lowest sheet resistance demonstrated so far exceeds that of the commercially available indium tin oxide. The possible cause of low conductivity lies in its intrinsic growth process, which requires further exploration. In this work, I have approached this problem by controlling graphene nucleation during the chemical vapor deposition process as well as by adopting three distinct procedures, including bis(trifluoromethanesulfonyl)amide doping, post annealing, and flattening of graphene films. Additionally, van der Waals stacked graphene layers have been prepared to reduce the sheet resistance effectively. I have demonstrated an efficient and flexible transparent conductor with the extremely low sheet resistance of 40 Ω sq?1, high transparency (Tr ≈90%), and high mechanical flexibility, making it suitable for electrode materials in future optoelectronic devices.
关键词： doping,flexibility,chemical vapor deposition,graphene,transparent conductors,sheet resistance
更新于2025-09-19 17:15:36
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Junction Welding Techniques for Metal Nanowire Network Electrodes
摘要： Transparent conductive electrodes (TCEs), which offer advantages of high electrical conductivity and optical transparency, are essential components of practical high-tech optoelectronics such as touch panels, e-papers, organic light-emitting diodes, and solar cells. Solution-processed Ag nanowires (AgNWs) have been considered as a practical alternative TCE material suitable for industrial-scale mass production. However, the contact resistance at AgNW junctions strongly affects the total sheet resistance of AgNW electrodes. In recent years, various welding techniques for AgNW network electrodes have been developed with the aim of decreasing their sheet resistance while maintaining their optical transmittance. In this paper, we present a review of various welding methods such as thermal-mechanical welding, light welding, chemical welding, and metal-plating welding.
关键词： silver nanowire,transparent conductive electrode,welding,sheet resistance,optical transmittance
更新于2025-09-19 17:15:36