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An analytical approach for modeling of high-efficiency crystalline silicon solar cells with homoa??hetero junctions
摘要： An analytical model based on charge neutrality principle and energy band diagram analysis is investigated to model a new structure of silicon heterojunction solar cell, which encompasses both homo and heterojunctions. In the analysed structure, a thin (pt)c-Si and a thin (nt)c-Si layers are used at front and back surfaces of (n)c-Si substrate respectively. The purpose of incorporating these layers is to reduce the solar cell output parameters sensitivity to a-Si:H/c-Si interface defect densities, increase the open circuit voltage eVocT and increase the fill factor (FFT. Since (n)c-Si silicon bulk becomes quasi neutral in the mentioned structure, charge neutrality equation can be separated as two independent equations for front and back surfaces. Solving charge neutrality equations, result in a-Si:H/c-Si interface potential, and subsequently charge concentration, electric field, surface recombination velocity, and open circuit voltage (Voc) calculation. Then, by adjusting doping concentration of the two additional layers, their effect on surface potential and energy band bending is studied. It is observed that (cid:0) 3, the Voc drops by when doping concentration of (pt)c-Si layer is increased from 1 ? 1018cm 15mV, and FF increases by 2:5%, while Voc and FF sensitivity to interface defects density is improved considerably. On the other hand, by (nt)c-Si layer insertion at back surface, in addition to decreasing sensitivity to interface defect densities in comparison to conventional SHJ silicon solar cell, Voc and FF are increased due to combination of high conductivity and enhancement of field effect passivation at back surface of solar cell. (cid:0) 3 Voc and FF Moreover, when doping concentration of (nt)c-Si layer increases from 1 ? 1018cm increases from 680 mV and 71% to 740 mV and 82% respectively.
关键词： HHJ silicon solar cell,(nt)c-Si layer,(pt)c-Si layer,Energy band diagram analysis,Charge neutrality principle
更新于2025-09-23 15:19:57
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Kinetic bandgap analysis of plasma photonic crystals
摘要： The dispersion relation of plasma and plasma-dielectric photonic multilayer structures is approached in terms of a one-dimensional Particle-in-Cell simulation. For several plasma-dielectric configurations, the system response is obtained using a pulsed excitation and a subsequent two-dimensional frequency analysis. It is first shown that the dispersion relation of a single, homogeneous plasma slab is well described by the cold-plasma model even at a low pressure of 1 Pa. The study is extended to the simulation of plasma photonic crystals with a variety of configurations based on the work of Hojo and Mase [J. Plasma Fusion Res. 80, 89 (2004)]. Considering a one-dimensional plasma photonic crystal made from alternating layers of dielectric and homogeneous plasma slabs, it is shown that the assumption of a cold-plasma description is well justified also in this case. Moreover, in this work, the results are reformatted and analyzed in a band diagram representation, in particular, based on the lattice constant a. Based on these considerations, a scaling invariant representation is presented, utilizing a generalized set of parameters. The study is completed with an exemplary comparison of three plasma-dielectric photonic crystal configurations and their corresponding band diagrams.
关键词： band diagram,Particle-in-Cell simulation,cold-plasma model,dispersion relation,plasma photonic crystals
更新于2025-09-10 09:29:36
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Unveiling the dual role of chemically synthesized copper doped zinc oxide for resistive switching applications
摘要： In this study, efforts were devoted to unveiling the dual role of single crystalline Cu (5%) doped ZnO (Cu:ZnO) synthesized by a simple and low-cost chemical process and to investigate its efficacy on resistive switching (RS) applications. It was found that when Cu:ZnO was annealed at a lower temperature of 450 °C and integrated onto ITO/glass for RS applications, only oxygen mediated vacancies were responsible for its resistive switching. However, ferroelectric properties have been observed when the same Cu:ZnO was annealed at a higher temperature of 800 °C and integrated onto Nb doped SrTiO3. X-ray diffraction, high resolution transmission electron microscope, x-ray photoelectron spectroscopy, UV-VIS-near infrared spectrometer, and piezoelectric force microscopy (PFM) were employed to study the crystallinity, interfaces, chemical compositions, bandgap, and domains in Cu:ZnO thin films, respectively. The bandgap of Cu:ZnO was found to be 3.20 eV. PFM study exhibits the domain inversion with 180° polarization inversion by applying an external bias, evidencing its effectiveness for memory applications. When the electrical characteristics were concerned, the RS device based on this ferroelectric Cu:ZnO offers better performance, such as lower SET/RESET voltages (～1.40 V), higher retention (up to 106 s) without distortion, and higher ON/OFF ratio (2.20 × 103), as compared to the former lower temperature annealed Cu:ZnO devices. A band-diagram was proposed, and transport studies were developed to understand the operational mechanism of these devices. This study explains both the limits and scopes of Cu:ZnO RS devices and formulates an idea which may accelerate the design of future generation devices.
关键词： copper doped zinc oxide,memory applications,band-diagram,resistive switching,ferroelectric properties
更新于2025-09-09 09:28:46