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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
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Frequency characteristics of a gas coupled-cavity ring laser
摘要： Based on a theoretical model describing the lasing dynamics in a gas ring laser (GRL) with coupled cavities, we have investigated the frequency characteristics of radiation. The conditions are found under which an increase in the scale factor is the largest. The regime of frequency locking of counterpropagating waves is studied. It is shown that the lock-in region in a GRL with an antiphase optical coupling of the cavities remains the same as without an additional cavity. The conditions are determined under which multistability of the radiation characteristics arises in a coupled-cavity GRL. In the numerical solution of the equations of the considered theoretical model, three branches of the frequency response are found.
关键词： multistability of radiation characteristics,gas ring laser,lock-in regime,coupled cavities,regime of beatings
更新于2025-09-16 10:30:52
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Economical generation regime of a supersonic continuous-wave chemical DF laser
摘要： We have performed experimental and computer-aided theoretical studies of the effect of the dilution degree y2 of a secondary fuel (deuterium) by an inert gas (helium) on the output characteristics of a supersonic cw chemical DF laser with a flat nozzle array, constructed in accordance with the nozzle – nozzle reagent mixing scheme. It is shown that an increase in the dilution degree in the range of 0 ￡ y2 ￡ 20 leads to a monotonous increase in the lasing zone length (a decrease in the radiation load on the resonator mirrors) and a drop in the laser specific energy output. With an increase in the optical path length (a decrease in the threshold gain), the sensitivity of the laser energy characteristics to the dilution degree decreases. Consequently, for a high-power DF laser (with a long nozzle array) with partial replacement of expensive deuterium with cheaper helium, a potential possibility for the implementation of an economical generation regime with acceptable specific energy output is achieved. The conditions for the implementation of this regime are identified.
关键词： economical generation regime,supersonic cw chemical DF laser,secondary fuel,inert diluent,energy characteristics,dilution degree,lasing zone length
更新于2025-09-16 10:30:52
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Electromagnetic Property of Coupled System of One-Dimensional Photonic Crystal
摘要： We propose and validate a novel coupled system of photonic crystals with four ports. The electromagnetically coupled waveguide system of microstrip lines with four ports is con?gured with a pair of closely aligned one-dimensional photonic crystals. The transmission characteristics between two ports are calculated by the method of moments and are observed by using a vector network analyzer. The special transmission characteristics of the coupled transmission line and the photonic crystal are observed. Outside the photonic band gap region, the transmission characteristics from the incident port on a transmission line to the exit port on the other line show re?ection characteristics that are unique to the photonic crystal. This is because only the odd modes are coupled between two closely aligned transmission lines. Inside the photonic band gap region, the transmission spectra become opaque because of the absence of electromagnetic modes.
关键词： photonic crystal,microstrip lines,electromagnetic modes,coupled system,transmission characteristics
更新于2025-09-16 10:30:52
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Investigation of InGaAs subcell to InGaP subcell in InGaP/InGaAs/Ge multijunction solar cells with Analytical framework
摘要： Solar radiation consists of different electromagnetic spectrum. Single junction solar cell restricts complete absorption of incident radiations. This limits the efficiency of the solar cells. The way to overcome this calamity is to segregate and classify the entire spectrum into several spectral tiny regions according respective band gaps inherently. This process gives birth to multi-junction solar cell. This paper describes the mathematical model for multi-junction metamorphic inverted solar cell. Starting from their primitive need, present work includes the photovoltaic effect to electroluminescence extinction. MATLAB simulation has been used to demonstrate the photo-voltage and electroluminescence intensity. It is observed from the obtained results that generated photo-voltage increases with the illumination power while the electroluminescence intensity decreases.
关键词： Analytical solution of multi-junction cell,Single-walled nanotube solar cell,Metamorphic inverted solar cell characteristics,Inverted structure,Multi-junction solar cell
更新于2025-09-16 10:30:52
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Disturbance Characteristics of the Off-Grid Photovoltaic System in the Frequency Range from 9 - 150 kHz with Changing Solar Irradiance and Shading Area
摘要： A solar power plant converts light into electricity using photovoltaics. It uses an inverter to convert DC to AC current to be connected to an AC load. Increasing use of solar panels in household application results in an increase in the use of inverters, in which some might due to the fact that inverters can produce disturbances at a frequency between 9-150 kHz. This study is focused on observing the disturbance characteristics of an off-grid photovoltaic system due to variations of irradiation and shading in the frequency range from 9 - 150 kHz. It is expected that the output of this observation can provide a reference for research in determining the effects on electric power system. This observation provided a shading effect of 0%, 25%, 50%, 75%, and 100% of the photovoltaic area and then conducted observation based on two solar irradiation conditions. Based on the observations, it is identified that in general there are 3 frequency ranges of dominant disturbances, they are: 20-25 kHz, 72-73 kHz, and 144-146 kHz. Their voltage disturbance will decrease with increasing shading area, where at shading conditions of 25% and 50% they will have a value voltage disturbance that tends to be the same as that in the 3 dominant frequency ranges.
关键词： disturbance characteristics,off-grid,shading area,photovoltaic system,solar irradiance
更新于2025-09-16 10:30:52
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Spectral characteristics of underwater laser-induced breakdown spectroscopy at high pressure conditions
摘要： Laser-induced breakdown spectroscopy (LIBS) has been proven to be an attractive technique for the in-situ oceanic applications. However, when applying LIBS into deep-sea, the pressure effect caused by different ocean depth is inescapable and could have great influence on the LIBS signals. In this work, spectral characteristics of underwater LIBS were investigated as a function of pressure in the range of 0.1–45 MPa. A high-pressure chamber built in the laboratory was used to simulate the high-pressure environment of deep-sea. Optimal laser energy and detection delay were first determined under different pressure conditions and were shown to be independent on the external pressure. The increase in pressure has a significant impact both on the peak intensity and line broadening of the observed spectra. The peak intensity of Na, Li and K lines increases with the increasing pressure until a maximum intensity reached at 12.5 MPa. Above this value, the peak intensity decreases gradually up to 45 MPa. For Ca line, the maximum intensity was observed at 30 MPa. The line broadening keeps constant at low pressures from 0.1 to 10 MPa while it increases linearly at higher pressures, indicating a higher electron density caused by the compression effect of the high external pressure. We also compared the spectral data obtained from the high-pressure chamber and from the field sea trials, and the good consistency between the laboratory data and sea-trial data suggested the key role of pressure effect on underwater LIBS signals for the practical deep-sea applications.
关键词： high-pressure chamber,underwater laser-induced breakdown spectroscopy,deep-sea application,pressure effect,spectral characteristics
更新于2025-09-16 10:30:52
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[IEEE 2019 International Conference on Power Electronics, Control and Automation (ICPECA) - New Delhi, India (2019.11.16-2019.11.17)] 2019 International Conference on Power Electronics, Control and Automation (ICPECA) - Droop based Low voltage ride through implementation for grid integrated photovoltaic system
摘要： This paper signi?es the development of an ef?cient and cost-effective control scheme for operation of grid integrated photovoltaic (PV) system under low voltage ride through (LVRT) condition. During LVRT If the PV system was to disconnect from the grid, the disconnection further aggravates the situation by causing larger disturbance than what was caused by the fault. To stabilize the system and prevent the ?ow of over current during LVRT it is necessary to control the reactive power injection in the system. The proposed scheme balances the active power though proportional gain regulation of plug in controller. Compared to the conventional LVRT method, this method is more cost effective. A normal maximum power point tracking (MPPT) scheme is implemented during normal operation. But in case of fault condition, an extra proportional controller is added to assist the droop characteristics of photovoltaic power voltage curve and attain system stability. Simulation has been performed on a grid integrated PV system of 4kW and LVRT conditions are tested. It is observed that the response of controller is fast and seamless during transition mode.
关键词： Active power control,Grid integrated photovoltaic(PV) system,Maximum power point tracking (MPPT),Droop characteristics,Low voltage ride through,Reactive power injection
更新于2025-09-16 10:30:52
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Effects of channel alternating corrugation on a laser beam propagation in plasmas
摘要： The propagation of an intense laser beam in an alternating corrugated plasma channel, which has a wide region and a narrow region in one corrugated space period, is investigated. Compared with the usual corrugated plasma channel, it is found that there are many more resonance peaks and many more abundant beat-like wave phenomena for the laser beam in this extended channel. Moreover, the much narrower region in some special alternating corrugated channels can play the role like a plasma lens for some laser beams, i.e., it can obviously change the laser spot size from small (large) to large (small) amplitude when the laser passes through the narrow region. These results are well confirmed by the final numerical simulations of wave equation and particle-in-cell approach.
关键词： Laser beam,Conversion,Resonance,Corrugated plasma channel,Propagation characteristics,Beat-like wave
更新于2025-09-16 10:30:52
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Solar Cells Based on Cu(In, Ga)Se2 Thin-Film Layers
摘要： This paper presents the results of experimental studies of spectral, dark current–voltage and light load characteristics of the selenide–copper–gallium–indium (Cu(In, Ga)Se2) solar cell. Тhe main fundamental parameters of the photoactive semiconductor layer Cu(In, Ga)Se2, such as the band gap, the resistivity of the layer, the equilibrium majority–carrier concentration, the lifetime and the product μ nτn of nonequilibrium minority carriers from the spectral, photoelectric and dark current–voltage characteristics are determined. Based on an analysis of the light-load current–voltage characteristics at various solar radiation powers (50–1000 W/m2), the main parameters of the p–n junction were determined, as well as the nonideality factor and the magnitude of the reverse diode saturation current; a photogeneration mechanism was established in the studied solar radiation range, which had the character of a diffusion mechanism, where carrier recombination in the photoactive layer did not have a significant effect. We found that in conditions of real solar lighting (Рrad = 50–1000 W/m2), the output parameters of the solar cell – short-circuit current, open circuit voltage, the maximum output power increases with Рrad. The fill factor (FF) of the light-current–voltage characteristics has a maximum at Рrad ≈ 200 W/m2, and an efficiency has a maximum value at Рrad ≈ 600 W/m2. The observed dependences of FF and efficiency are explained by the dependence of the series (Rser) and shunt (Rsh) resistance of a solar cell on Prad. To maintain the efficiency of a solar cell based on thin-film layers Cu(In, Ga)Se2, equally high in conditions of increased radiation, as well as in conditions of low solar radiation, it is necessary that Rser decreases and Rsh does not change with Prad.
关键词： photoactive thin film layer,series resistance,solar cell,Cu(In, Ga)Se2,fill factor,short circuit current,solar radiation power,light current–voltage characteristics,efficiency,open circuit voltage,shunt resistance
更新于2025-09-16 10:30:52