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RF Characterization of NiO and TiO <sub/>2</sub> Based Metal-Insulator-Metal (MIM) Diodes on Flexible Substrates
摘要： This paper presents the fabrication and characterization of metal-insulator-metal (MIM) diodes on flexible substrates for RF and microwave circuit applications. Diodes using two types of insulators, titanium dioxide (TiO2) and nickel oxide (NiO), are investigated. These insulators are obtained using different oxidation techniques, i.e., in-situ oxidation for TiO2 and plasma oxidation for NiO. Asymmetric metal contacts (Ti-TiO2-Pd and Ni-NiO-Mo) are utilized to achieve nonlinear I–V characteristics. The fabricated diodes show strong non-linearity, high current densities, and low turn-ON voltage. The diodes show RF to dc rectification with near-ideal behavior and rectification sensitivity of 22 V/W (18 GHz) and 46 V/W (18 GHz) for TiO2 and NiO, respectively. NiO-based diodes barrier shows higher current density and higher cutoff frequency in comparison with TiO2 as expected diodes due to thinner oxide and lower dielectric constant. The diodes also work well as frequency doublers over a wide frequency range of 1–4 GHz for TiO2 and 2–10 GHz for NiO-based diodes. Good dc and RF performance of diodes indicate that good quality oxide can be achieved on plastic substrates and MIM devices can provide a perfect solution for RF and microwave circuits on a flexible substrate.
关键词： MIM diodes,rectification,Flexible electronics,harmonic generation,thin film devices,microwave circuits
更新于2025-09-23 15:23:52
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Optoelectronic Characterization of Emerging Solar Absorber Cu <sub/>3</sub> AsS <sub/>4</sub>
摘要： Enargite Cu3AsS4 is a promising absorber for thin-film solar cells but little is known about its optoelectronic properties. Here, we present photoluminescence (PL) spectroscopy, time-resolved terahertz spectroscopy (TRTS), time-resolved photoluminescence (TRPL) spectroscopy, and cyclic voltammetry (CV) measurements of enargite thin films. The results indicate promising defect characteristics with minority carrier lifetimes on the order of ns, and band alignments suggest that buffer layers besides CdS must be developed to achieve high efficiency Cu3AsS4 solar cells.
关键词： photovoltaic cells,copper compounds,thin film devices,semiconductor materials,nanocrystals
更新于2025-09-23 15:21:01
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[BestMasters] Topographic Organization of the Pectine Neuropils in Scorpions (An Analysis of Chemosensory Afferents and the Projection Pattern in the Central Nervous System) || Pyroelectric Sensor for Characterization of Biological Cells
摘要： Nowadays, cell characterization represents a fundamental task widely diffused in different fields. The main purpose of this paper is the design and development of a device for cellular characterization based on a pyroelectric sensor. After a brief introduction dedicated to the methods actually employed for cell counting, the pyroelectric sensor, the electronic readout unit, and the prototype will be introduced. Different cell concentration samples have been analyzed in order to highlight how the induced pyroelectric response is related to the cell properties. Experimental results shown that sensor output is strongly affected by cell type, concentration and viability. Particularly, it has been observed an increase in output signal related to an increase in cell concentration, mainly due to a lower thermal conductivity. No significant variation has been observed by the drastic reduction of cell viability also by varying cell concentration. The aforementioned results are probably due to the induction of a decrease in mitochondrial activity. Obtained results are very promising for the realization of a low cost laboratory device with all the characteristics listed above.
关键词： Sensor phenomena and characterization,Pyroelectric sensor,Thermal factors,Counting circuits,Cellular biophysics,Biological cell characterization,Thin film devices
更新于2025-09-19 17:15:36
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Color Quantification for Process Monitoring and Appearance Control of Thin Film PV
摘要： Product color and appearance uniformity are a critical manufacturing consideration in any industry, including solar module manufacturing. These considerations become even more important as modules are increasingly installed in locations where aesthetics is a prime consideration, such as BIPV, automotive, and consumer products. Additionally, the interaction of PV materials with visible light enables objective color characterization to be a useful tool for control of film deposition processes. In this paper we describe our efforts, learning and results controlling product color and using color as a process monitoring and control tool.
关键词： optical reflection,color,photovoltaic cells,thin film devices,process control
更新于2025-09-19 17:13:59
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Material Property Changes in Defects Caused by Reverse Bias Exposure of CIGS Solar Cells
摘要： Partial shading of Cu(In,Ga)Se2 modules can lead to the formation of reverse bias induced wormlike defects. These wormlike defects act as local shunts and permanently decrease module output. A good understanding of the formation and propagation mechanisms of these defects is needed in order to mitigate the negative effects, or to prevent these defects from forming. In this article, wormlike defects were formed on small nonencapsulated cells by exposing them to reverse bias conditions. Scanning electron microscopy-energy-dispersive X-ray spectroscopy measurements showed a rearrangement of elements: Indium, gallium, and copper were replaced by cadmium, whereas selenium was replaced by sulfur in the area around the defect. Moreover, additional electronic-defect levels were found in that area with spectrally resolved photoluminescence spectroscopy. Based on the material changes in the area close to the wormlike defects, a propagation mechanism is proposed. The model assumes a chemical reaction as the driving force for propagation instead of melting because of ohmic heating.
关键词： photoluminescence (PL),photovoltaic (PV) cells,electric breakdown,reliability,thin film devices,Cadmium
更新于2025-09-12 10:27:22
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Optoelectronics - Advanced Device Structures || Hybrid Silicon-Organic Heterojunction Structures for Photovoltaic Applications
摘要： The concept for inorganic-organic device is an attractive technology to develop devices with better characteristics and functionality due to the complementary advantages of inorganic and organic materials. This chapter provides an overview of the principal requirements for organic and inorganic semiconductor properties and their fabrication processes and focus on the compatibility between low temperature plasma enhanced chemical vapor deposition (PECVD) and polymer organic materials deposition. The concept for inorganic-organic device was validated with the fabrication of three hybrid thin film photovoltaic structures, based on hydrogenated silicon (Si:H), organic poly(3-hexythiophene): methano-fullerenephenyl-C61-butyric-acid-methyl-ester (P3HT:PCBM), and poly(3,4ethylenedioxythiophene): poly(4-styrenesulfonate) (PEDOT:PSS) films. Optoelectronic characteristics, performance characteristics, and interfaces of the different configurations aspects are discussed. Hybrid ITO/PEDOT:PSS/(i)Si:H/(n)Si:H structure results in a remarkably high short circuit current density as large as 17.74 mA/cm2, which is higher than the values in organic or inorganic reference samples. Although some hybrid structures demonstrated substantial improvement of performance, other hybrid structures showed poor performance, further R&D efforts seem to be promising, and should be focused on deeper study of organic materials and related interface properties.
关键词： thin film devices,hybrid devices,plasma deposited materials,solar cells,organic semiconductors
更新于2025-09-11 14:15:04
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Simulated and Real Sheet-of-Light 3D Object Scanning Using a-Si:H Thin Film PSD Arrays
摘要： A MATLAB/SIMULINK software simulation model (structure and component blocks) has been constructed in order to view and analyze the potential of the PSD (Position Sensitive Detector) array concept technology before it is further expanded or developed. This simulation allows changing most of its parameters, such as the number of elements in the PSD array, the direction of vision, the viewing/scanning angle, the object rotation, translation, sample/scan/simulation time, etc. In addition, results show for the first time the possibility of scanning an object in 3D when using an a-Si:H thin film 128 PSD array sensor and hardware/software system. Moreover, this sensor technology is able to perform these scans and render 3D objects at high speeds and high resolutions when using a sheet-of-light laser within a triangulation platform. As shown by the simulation, a substantial enhancement in 3D object profile image quality and realism can be achieved by increasing the number of elements of the PSD array sensor as well as by achieving an optimal position response from the sensor since clearly the definition of the 3D object profile depends on the correct and accurate position response of each detector as well as on the size of the PSD array.
关键词： three-dimensional sensing,arrays,three-dimensional image acquisition,three-dimensional image processing,thin film devices and applications,optical sensing and sensors
更新于2025-09-04 15:30:14