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Theoretical investigation of broadband absorption enhancement in a-Si thin-film solar cell with nanoparticles
摘要： Thin-film solar cells have attracted increasing attention due to its low material cost and large flexibility, but they also face the challenge of low solar absorption due to reduced active layer thickness. Through exciting surface plasmon resonance, plasmonic metal nanoparticles are usually placed on the cell front surface to enhance solar absorption. However, if eliminating the unuseful intrinsic absorption in nanoparticles, we find that dielectric ones are better choices to enhance a-Si thin-film solar cell absorption efficiency. Moreover, a composite light trapping structure with dielectric nanoparticles on the front surface and metal hemispheres on the rear surface is proposed to achieve broadband absorption enhancement in both short and long wavelengths, with the aim to get a higher conversion efficiency. The finite-difference-time-domain simulation results show that, compared with bare 100-nm-thick amorphous silicon solar cell, the short-circuit current density and photoelectric conversion efficiency could be respectively improved by 21% and 18% with addition of optimized composite light trapping structure. The general method proposed in this study could provide valuable guidance to light trapping structure design for various kinds of thin-film solar cells.
关键词： Broadband absorption enhancement,Thin-film solar cell,Light trapping,Conversion efficiency,Amorphous silicon,Nanoparticle
更新于2025-09-19 17:13:59
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[IEEE 2019 International Energy and Sustainability Conference (IESC) - Farmingdale, NY, USA (2019.10.17-2019.10.18)] 2019 International Energy and Sustainability Conference (IESC) - Methodology for the implementation of photovoltaic energy in a microgrid
摘要： A new accurate voltage-programmed pixel circuit for active-matrix organic light-emitting diode (AMOLED) displays is presented. Composed of three TFTs and one storage capacitor, the proposed pixel circuit is implemented both in a-Si and a-IGZO TFT technologies for the same pixel size for fair comparison. The simulation result for the a-Si-based design shows that, during a programming time of 90 s, the pixel circuit was able to compensate for a 3 V threshold voltage ( ) shift of the drive TFT with almost no error. In contrast, the a-IGZO-based pixel circuit, has a larger current error (of around 8%), despite its proven three-fold higher speed.
关键词： Active-matrix organic light-emitting diode (AMOLED),compensation,oxide thin-film transistor (TFT),amorphous silicon (a-Si)
更新于2025-09-19 17:13:59
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Permanent Optimization of Large-FSR Dual-Microring Bandpass Filters
摘要： Energy-ef?cient communication links are crucial for future processors and optoelectronic microchips in order to continue growths in computing and information technologies [1]. Wavelength-division multiplexing (WDM) techniques based on silicon photonic circuits are ideal for high bandwidths data communication systems with small footprints [2,3]. Compact double ring resonators (DRRs) provide excellent properties to realize spectral ?lters with ?at-top transmission characteristics, providing a steep roll-off with low channel crosstalk at dense frequency grids. Hence, cascaded DRRs as illustrated in Fig. 1 (a) are well-suited for integrated WDM systems on optoelectronic microchips. The high refractive index of silicon facilitates small ring perimeters and the wide free spectral range (FSR ∝ 1 Lr ) enables multiplexing tens of data channels to a common bus waveguide. The high energy-ef?ciency which is enhanced by the strong thermo-optic effect (TOE) combined with the short physical lengths is another relevant advantage of the compact size. However, manufacturing variability and associated photonic component deviations remain a serious drawback [4]. Hence, most recent works use thermal heaters for the dynamic ?lter control as well as to counterbalance inevitable manufacturing deviations [5-7]. In this work, we present multilayer compatible 5 and 10μm radius DRR ?lters based on microrings manufactured with deposited amorphous silicon [8]. We demonstrate a permanent correction of manufacturing variations and optimize the spectral properties of DRR ?lters. Such fabrication imperfections which may arise more frequently in multilayer circuits are exempli?ed in Fig. 1 (a) where widths (Δw), heights (Δh), and refractive index (Δn) variations are implemented to one microring; even lowest deviations substantially degrade the ?lter response. A DRR measurement with undesired drop port splitting which was corrected through the SiO2 top cladding by 405 nm laser-trimming one of the rings is shown in Fig. 1 (b); the intermediate trimming spectra are provided in order to guide the eye. The possibility to permanently align ?lters to a given wavelength channel is presented in Fig. 1 (c). In this experiment both 5 μm radius racetracks were alternately trimmed to shorter wavelengths, without degrading the spectrum or the ?lter bandwidths. In summary, several compact DRR ?lters with multiplexers up to 8-channels suitable for multilayer integration at the CMOS back-end-of-line with start-of-art performance were successfully fabricated and tested. Malfunctioning components were identi?ed and optimized on micron-scales by a post-fabrication trimming method. The proposed correction method for DRR multiplexers allows adjusting ?lters to a prespeci?ed wavelength channel and enables more generalized concepts which do not require a thermal heater for each ring thereby mitigating detrimental thermal crosstalk and lowering the overall energy consumption.
关键词： manufacturing variability,Wavelength-division multiplexing (WDM),spectral ?lters,double ring resonators (DRRs),silicon photonic circuits,thermal heaters,Energy-ef?cient communication links,laser-trimming,amorphous silicon,CMOS back-end-of-line
更新于2025-09-16 10:30:52
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Through Concentration Profiling of Heterojunction Solar Cells
摘要： Electrochemical capacitance–voltage profiling has been used to examine heterojunction solar cells based on single-crystal silicon. Specific features of the electrochemical capacitance–voltage profiling of modern multilayer heterojunction solar cells have been analyzed. The distribution profiles of majority carriers across the whole thickness of the samples were obtained, including, for the first time, those in layers of conducting indium tin oxide.
关键词： electrochemical capacitance–voltage profiling,single-crystal silicon,amorphous silicon,heterojunction solar cells
更新于2025-09-16 10:30:52
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Hybrid External Cavity Laser with an Amorphous Silicon-Based Photonic Crystal Cavity Mirror
摘要： The authors present results on the performance of a hybrid external cavity photonic crystal laser-comprising semiconductor optical ampli?er, and a 2D photonic crystal cavity fabricated in low-temperature amorphous silicon. The authors demonstrate that lithographic control over amorphous silicon photonic crystal cavity-resonant wavelengths is possible, and that single-mode lasing at optical telecommunications wavelengths is possible on an amorphous silicon platform.
关键词： nanophotonics,silicon photonics,amorphous silicon,CMOS processing,photonic crystals,telecommunications,lasers
更新于2025-09-16 10:30:52
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Sensors, Circuits and Instrumentation Systems (2018) || Investigation of Optoelectronic Properties of Amorphous Silicon Germanium Photodetectors
摘要： Cost consideration of the development of electronic devices is one of prime importance. One simple approach to lower the cost of production of photovoltaic and detectors is by using low cost materials such as amorphous silicon and germanium. These two semiconductors have different optoelectronic properties, such as energy gap, photoconductivity and absorption coefficient. The use of an alloy from the mixing of silicon with certain percentages of germanium would produce photodetectors with improved electronic characteristics and photoconductivity. A number of a-SiGe alloy thin films with different quantities of germanium have been fabricated using thermal vacuum evaporation technique. Conduction mechanism and activation energy of the prepared samples had been calculated and analyzed. The I–V characteristics, the photogenerated current and detectivity of these samples are subjected to measurement and discussion. Hall measurements are also conducted so to calculate the Hall I–V characteristics, Hall mobility, carrier concentration and type identification of the samples.
关键词： Amorphous silicon germanium photodetector,photoconductivity,detectivity,Hall measurements,activation energy,conduction mechanism
更新于2025-09-16 10:30:52
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Thermal Activation of Boron- and Phosphorus-Doped Amorphous Silicon and the Contribution to Improved Efficiency in Hydrogenated Amorphous Silicon Solar Cells
摘要： Hydrogenated amorphous silicon (a-Si:H) is an interesting candidate as an absorber material for solar cells. Despite the wealth of research to improve the e?ciency of a-Si:H solar cells by improving either the material quality of the absorber layer or by means of light trapping approaches, e?orts to improve the e?ciency by means of doped layer manipulation are relatively rare. In this work, single-junction a-Si:H solar cells with improved e?ciency due to thermal activation of doped layers via thermal annealing will be presented. Temperature-dependent dark conductivity measurements revealed that p- and n-type doped a-Si:H materials show di?erent equilibrium temperatures. External quantum e?ciency at di?erent annealing temperatures revealed that front surface collection probability was improved with the activation of a p layer, after which the collection probability of the back surface was improved with the activation of an n layer.
关键词： Dopant activation,Amorphous silicon,Solar cells
更新于2025-09-16 10:30:52
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Simulation and analysis on device parameter variations of single junction hydrogenated amorphous silicon solar cell
摘要： A novel single junction amorphous silicon solar cell is investigated by numerical simulation tool AFORS-HET to understand the influence of various parameters such as bandgap, different layer thickness, doping concentrations of P and N layers, transparent conducting oxides as textured and plane surfaces with graded structures on efficiency of solar cell. The trade-off between input parameters were examined in terms of short circuit current density (Jsc), open circuit voltage (Voc), Fill Factor (FF) and efficiency (η) as a function of different structural variations for efficiency enhancement. The systematic approach from front to back layer is investigated and the output parameters are tabulated with varied layer configurations to get clear understanding on the relative improvements over the input parameter variations. Simulated results show that maximum of 8.04% and 11.03% efficiency is seen by graded and textured structures respectively compared to maximum 3.46% efficiency of standard p-i-n structure. A structure with combination of graded and textured layers could provide maximum efficiency up to 19.08% is presented.
关键词： Amorphous silicon,AFORS HET,a-Si:H parameters,P-I-N solar cell,Thin film,Photovoltaics
更新于2025-09-16 10:30:52
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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) - Modeling Methodology for Determining Energy Collection Potential of Photovoltaics Applied To Curved Surfaces
摘要： Arrays of periodic one-dimensional nanomaterials offer tunable optical properties in terms of light–matter interaction which are attractive for designing efficient optoelectronic devices. This paper presents a fabrication of bottom-up grown nanopillar (NP) array solar cells based on n-i-p thin-film amorphous silicon using scaffolds of vertically aligned carbon nanotube (CNT) array. The effects of varying the CNT spacing over the range from 800 to 2000 nm on optical and electrical properties of the solar cells were investigated. The NP solar cell with CNT spacing of 800 nm exhibited ‘moth-eye’ broadband antireflection behavior, showing an average reflectance value lower than 10%. The enhanced optical absorption translated to significant enhancements in photocurrent and quantum efficiency compared to a conventional planar solar cell under low light condition. The open-circuit voltage (Voc) of the NP solar cell was found systematically correlated with the CNT spacing and the illumination condition. The results presented here is of importance for developing high efficiency one-dimensional nanostructured solar cells.
关键词： photovoltaic cells,nanostructured materials,nanophotonics,Amorphous silicon,carbon nanotube (CNT)
更新于2025-09-16 10:30:52
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Synthesis of Lithography Free Micro-Nano Electron Field Emitters Using Pulsed KrF Laser Assisted Metal Induced Crystallization of Thin Silicon Films
摘要： Hydrogenated amorphous thin silicon films (a-Si:H) deposited on metal coated glass substrates were investigated to analyze the effect of a novel processing technique called Laser Assisted Metal Induced Crystallization (LAMIC) on their electron field emission (FE) properties. Post-surface characterization of the processed films showed increased surface roughness and the presence of uniformly spaced “island-like” micro-nano structures on the surface of metal coated backplane samples. Best FE results were obtained from samples sputtered with a thin layer of Aluminum (Al) on top and cross laser annealed at 190 mJ/cm2 (y-axis) and 100 mJ/cm2 (x-axis). FE measurements indicate a low turn-on electric field of less than 16 V/mm with emission currents in the order of 10?6 A. FE results were found to be particularly dependent on the laser fluence and the surface morphology exhibited very high discharge resistance. Oxidation of the films was observed to deteriorate their FE characteristics, thereby increasing the emission threshold to 36 V/mm. Diode configured field emission display prototypes are fabricated to exemplify their potential as cold cathode emitters.
关键词： excimer laser crystallization,electron field emission,metal induced crystallization,micro-nano emitters,Hydrogenated amorphous silicon
更新于2025-09-16 10:30:52