This paper presents a brief overview of several promising design technologies for high efficiency silicon-based radio frequency （RF） power amplifiers （PAs） as well as the use of these technologies in mobile broadb...This paper presents a brief overview of several promising design technologies for high efficiency silicon-based radio frequency （RF） power amplifiers （PAs） as well as the use of these technologies in mobile broadband wireless communications. Four important aspects of PA design are addressed in this paper. First, we look at class-E PA design equations and provide an example of a class-E PA that achieves efficiency of 65-70% at 2.4 GHz. Then, we discuss state-of-the-art envelope tracking （ET） design for monolithic wideband RF mobile transmitter applications. A brief overview of Doherty PA design for the next-generation wireless handset applications is then given. Towards the end of the paper, we discuss an inherently broadband and highly efficient class-J PA design targeting future multi-band multi-standard wireless communication protocols.展开更多
In this work, we study the method for determining the maximum of the minority carrier recombination velocity at the junction Sfmax, corresponding to the maximum power delivered by the photovoltaic generator. For this,...In this work, we study the method for determining the maximum of the minority carrier recombination velocity at the junction Sfmax, corresponding to the maximum power delivered by the photovoltaic generator. For this, we study the temperature influence on the behavior of the front white biased solar cell in steady state. By solving the continuity equation of excess minority carrier in the base, we have established the expressions of the photocurrent density, the recombination velocity on the back side of the base Sb, and the photovoltage. The photocurrent density and the photovoltage are plotted as a function of Sf, called, minority carrier recombination velocity at the junction surface, for different temperature values. The illuminated I-V characteristic curves of the solar cell are then derived. To better characterize the solar cell, we study the electrical power delivered by the base of the solar cell to the external charge circuit as either junction surface recombination velocity or photovoltage dependent. From the output power versus junction surface recombination velocity Sf, we have deduced an eigenvalue equation depending on junction recombination velocity. This equation allows to obtain the maximum junction recombination velocity Sfmax corresponding to the maximum power delivered by the photovoltaic generator, throughout simulink model. Finally, we deduce the conversion efficiency of the solar cell.展开更多
The aim of this study is to determinate the electrical parameters of a white biased silicon solar cell submitted to an irradiation energy of particles (protons, helium, electrons and heavy ions). A theoretical study o...The aim of this study is to determinate the electrical parameters of a white biased silicon solar cell submitted to an irradiation energy of particles (protons, helium, electrons and heavy ions). A theoretical study of the influence of irradiation energy on the photocurrent density, the photovoltage, the maximum power, as well as the maximum efficiency of the solar cell is presented through a resolution of the continuity equation relative to excess minority carrier. Then the expressions of the photocurrent density Jph, the photovoltage Vph, and the excess minority carrier recombination velocity at the back side Sb are established dependent of irradiation parameters ∅p, Kl respectively irradiation flux and intensity. In this work, we propose a method for determining the recombination velocity of the excess minority carrier at the junction Sfmax corresponding to the maximum power point delivered by the photovoltaic generator under the influence of the irradiation. It is then obtained by calculating the derivative of the power with respect to the excess minority carrier recombination velocity Sf at the junction emitter-base. A transcendental equation solution is deduced as eigenvalue, leading to the junction recombination velocity of excess minority carrier and also yields the solar cell maximum conversion efficiency.展开更多
A possible heating effect on the process of high deposition rate microcrystalline silicon has been studied. It includes the discharge time-accumulating heating effect, discharge power, inter-electrode distance, and to...A possible heating effect on the process of high deposition rate microcrystalline silicon has been studied. It includes the discharge time-accumulating heating effect, discharge power, inter-electrode distance, and total gas flow rate induced heating effect. It is found that the heating effects mentioned above are in some ways quite similar to and in other ways very different from each other. However, all of them will directly or indirectly cause the increase of the substrate surface temperature during the process of depositing microcrystalline silicon thin films, which will affect the properties of the materials with increasing time. This phenomenon is very serious for the high deposition rate of microcrystalline silicon thin films because of the high input power and the relatively small inter-electrode distance needed. Through analysis of the heating effects occurring in the process of depositing microcrystalline silicon, it is proposed that the discharge power and the heating temperature should be as low as possible, and the total gas flow rate and the inter-electrode distance should be suitable so that device-grade high quality deposition rate microcrystalline silicon thin films can be fabricated.展开更多
Wide bandgap semiconductor materials are driving revolutionary improvements in the performance of high-power electronic devices. This study systematically evaluates the application prospects of wide bandgap semiconduc...Wide bandgap semiconductor materials are driving revolutionary improvements in the performance of high-power electronic devices. This study systematically evaluates the application prospects of wide bandgap semiconductor materials in high-power electronic devices. The research first compares the physical properties of major wide bandgap materials (such as silicon carbide SiC and gallium nitride GaN), analyzing their advantages over traditional silicon materials. Through theoretical calculations and experimental data analysis, the study assesses the performance of these materials in terms of high breakdown field, high thermal conductivity, and high electron saturation velocity. The research focuses on the application of SiC and GaN devices in power electronics, including high-voltage DC transmission, electric vehicle drive systems, and renewable energy conversion. The study also discusses the potential of wide bandgap materials in RF and microwave applications. However, the research also points out the challenges faced by wide bandgap semiconductor technology, such as material defect control, device reliability, and cost issues. To address these challenges, the study proposes solutions, including improving epitaxial growth techniques, optimizing device structure design, and developing new packaging methods. Finally, the research looks ahead to the prospects of wide bandgap semiconductors in emerging application areas such as quantum computing and terahertz communications. This study provides a comprehensive theoretical foundation and technology roadmap for the application of wide bandgap semiconductor materials in high-power electronic devices, contributing to the development of next-generation high-efficiency energy conversion and management systems.展开更多
The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V ch...The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V characteristics. After the resolution of the magneto transport equation and continuity equation of excess minority carriers in the base of the bifacial silicon solar cell under multispectral illumination, the photo-current density and the photovoltage are determined and the J-V and P-V curves are plotted. Using simultaneously the J-V and P-V curves, we determine, according to magnetic field intensity, the peak photocurrent density, the peak photovoltage, the peak electric power, the fill factor and the load resistance at the peak power point. The numerical data show that the solar cell’s peak power decreases with magnetic field intensity while the fill factor and the load resistance increase.展开更多
100-W class power storage systems were developed, which comprised spherical Si solar cells, a maximum power point tracking charge control-ler, a lithium-ion battery, and one of two different types of direct current (D...100-W class power storage systems were developed, which comprised spherical Si solar cells, a maximum power point tracking charge control-ler, a lithium-ion battery, and one of two different types of direct current (DC)-alter- nating current (AC) converters. One inverter used SiC met-al-oxide-semicon-ductor field-effect transistors (MOSFETs) as switching devices while the other used Si MOSFETs. In these 100-W class inverters, the ON resistance was considered to have little influence on the efficiency. Nevertheless, the SiC-based inverter exhibited an approximately 3% higher DC-AC conversion efficiency than the Si-based inverter. Power loss analysis indicated that the higher efficiency resulted predominantly from lower switching and reverse recovery losses in the SiC MOSFETs compared with in the Si MOSFETs.展开更多
The objective of the paper is to report results on fabrication, structural, morphological and performance characteristics of novel TiO2/PS/Si, Au/TiO2/PS/Si and Au/PS/Si direct ammonia fuel cells (DAFC) using nanoporo...The objective of the paper is to report results on fabrication, structural, morphological and performance characteristics of novel TiO2/PS/Si, Au/TiO2/PS/Si and Au/PS/Si direct ammonia fuel cells (DAFC) using nanoporous silicon (PS) as proton conducting membrane (instead of traditional polymer Nafion membrane) and TiO2, Au/TiO2 or Au as catalyst layer. Porous silicon layers have been prepared by electrochemical modification of silicon substrates. Films containing titanium dioxide are more efficient catalysts for hydrogen production from ammonia solution. The Au/ TiO2/PS/Si cell exhibited the open circuit voltage 0.87 V and performance of 1.6 mW/cm2 with 50% ammonia solution as fuel at room temperature. Mechanisms of proton transport in nanoporous silicon membrane and generation of electricity in DAFC have been considered. Advantages of investigated direct ammonia fuel cells consist in simplicity of fabrication technology, which can be integrated into standard silicon micro fabrication processes and operation of cells at room temperature. The work demonstrates that the PS based fuel cells have potential for portable applications.展开更多
文摘This paper presents a brief overview of several promising design technologies for high efficiency silicon-based radio frequency （RF） power amplifiers （PAs） as well as the use of these technologies in mobile broadband wireless communications. Four important aspects of PA design are addressed in this paper. First, we look at class-E PA design equations and provide an example of a class-E PA that achieves efficiency of 65-70% at 2.4 GHz. Then, we discuss state-of-the-art envelope tracking （ET） design for monolithic wideband RF mobile transmitter applications. A brief overview of Doherty PA design for the next-generation wireless handset applications is then given. Towards the end of the paper, we discuss an inherently broadband and highly efficient class-J PA design targeting future multi-band multi-standard wireless communication protocols.
文摘In this work, we study the method for determining the maximum of the minority carrier recombination velocity at the junction Sfmax, corresponding to the maximum power delivered by the photovoltaic generator. For this, we study the temperature influence on the behavior of the front white biased solar cell in steady state. By solving the continuity equation of excess minority carrier in the base, we have established the expressions of the photocurrent density, the recombination velocity on the back side of the base Sb, and the photovoltage. The photocurrent density and the photovoltage are plotted as a function of Sf, called, minority carrier recombination velocity at the junction surface, for different temperature values. The illuminated I-V characteristic curves of the solar cell are then derived. To better characterize the solar cell, we study the electrical power delivered by the base of the solar cell to the external charge circuit as either junction surface recombination velocity or photovoltage dependent. From the output power versus junction surface recombination velocity Sf, we have deduced an eigenvalue equation depending on junction recombination velocity. This equation allows to obtain the maximum junction recombination velocity Sfmax corresponding to the maximum power delivered by the photovoltaic generator, throughout simulink model. Finally, we deduce the conversion efficiency of the solar cell.
文摘The aim of this study is to determinate the electrical parameters of a white biased silicon solar cell submitted to an irradiation energy of particles (protons, helium, electrons and heavy ions). A theoretical study of the influence of irradiation energy on the photocurrent density, the photovoltage, the maximum power, as well as the maximum efficiency of the solar cell is presented through a resolution of the continuity equation relative to excess minority carrier. Then the expressions of the photocurrent density Jph, the photovoltage Vph, and the excess minority carrier recombination velocity at the back side Sb are established dependent of irradiation parameters ∅p, Kl respectively irradiation flux and intensity. In this work, we propose a method for determining the recombination velocity of the excess minority carrier at the junction Sfmax corresponding to the maximum power point delivered by the photovoltaic generator under the influence of the irradiation. It is then obtained by calculating the derivative of the power with respect to the excess minority carrier recombination velocity Sf at the junction emitter-base. A transcendental equation solution is deduced as eigenvalue, leading to the junction recombination velocity of excess minority carrier and also yields the solar cell maximum conversion efficiency.
基金Project supported by Hi-Tech Research and Development Program of China (Grant Nos. 2007AA05Z436 and 2009AA050602)Science and Technology Support Project of Tianjin (Grant No. 08ZCKFGX03500)+3 种基金National Basic Research Program of China(Grant Nos. 2006CB202602 and 2006CB202603)National Natural Science Foundation of China (Grant No. 60976051)International Cooperation Project between China-Greece Government (Grant Nos. 2006DFA62390 and 2009DFA62580)Program for New Century Excellent Talents in University of China (Grant No. NCET-08-0295)
文摘A possible heating effect on the process of high deposition rate microcrystalline silicon has been studied. It includes the discharge time-accumulating heating effect, discharge power, inter-electrode distance, and total gas flow rate induced heating effect. It is found that the heating effects mentioned above are in some ways quite similar to and in other ways very different from each other. However, all of them will directly or indirectly cause the increase of the substrate surface temperature during the process of depositing microcrystalline silicon thin films, which will affect the properties of the materials with increasing time. This phenomenon is very serious for the high deposition rate of microcrystalline silicon thin films because of the high input power and the relatively small inter-electrode distance needed. Through analysis of the heating effects occurring in the process of depositing microcrystalline silicon, it is proposed that the discharge power and the heating temperature should be as low as possible, and the total gas flow rate and the inter-electrode distance should be suitable so that device-grade high quality deposition rate microcrystalline silicon thin films can be fabricated.
文摘Wide bandgap semiconductor materials are driving revolutionary improvements in the performance of high-power electronic devices. This study systematically evaluates the application prospects of wide bandgap semiconductor materials in high-power electronic devices. The research first compares the physical properties of major wide bandgap materials (such as silicon carbide SiC and gallium nitride GaN), analyzing their advantages over traditional silicon materials. Through theoretical calculations and experimental data analysis, the study assesses the performance of these materials in terms of high breakdown field, high thermal conductivity, and high electron saturation velocity. The research focuses on the application of SiC and GaN devices in power electronics, including high-voltage DC transmission, electric vehicle drive systems, and renewable energy conversion. The study also discusses the potential of wide bandgap materials in RF and microwave applications. However, the research also points out the challenges faced by wide bandgap semiconductor technology, such as material defect control, device reliability, and cost issues. To address these challenges, the study proposes solutions, including improving epitaxial growth techniques, optimizing device structure design, and developing new packaging methods. Finally, the research looks ahead to the prospects of wide bandgap semiconductors in emerging application areas such as quantum computing and terahertz communications. This study provides a comprehensive theoretical foundation and technology roadmap for the application of wide bandgap semiconductor materials in high-power electronic devices, contributing to the development of next-generation high-efficiency energy conversion and management systems.
文摘The aim of this work is to present a theoretical study of external magnetic field effect on a bifacial silicon solar cell’s electrical parameters (peak power, fill factor and load resistance) using the J-V and P-V characteristics. After the resolution of the magneto transport equation and continuity equation of excess minority carriers in the base of the bifacial silicon solar cell under multispectral illumination, the photo-current density and the photovoltage are determined and the J-V and P-V curves are plotted. Using simultaneously the J-V and P-V curves, we determine, according to magnetic field intensity, the peak photocurrent density, the peak photovoltage, the peak electric power, the fill factor and the load resistance at the peak power point. The numerical data show that the solar cell’s peak power decreases with magnetic field intensity while the fill factor and the load resistance increase.
文摘100-W class power storage systems were developed, which comprised spherical Si solar cells, a maximum power point tracking charge control-ler, a lithium-ion battery, and one of two different types of direct current (DC)-alter- nating current (AC) converters. One inverter used SiC met-al-oxide-semicon-ductor field-effect transistors (MOSFETs) as switching devices while the other used Si MOSFETs. In these 100-W class inverters, the ON resistance was considered to have little influence on the efficiency. Nevertheless, the SiC-based inverter exhibited an approximately 3% higher DC-AC conversion efficiency than the Si-based inverter. Power loss analysis indicated that the higher efficiency resulted predominantly from lower switching and reverse recovery losses in the SiC MOSFETs compared with in the Si MOSFETs.
文摘The objective of the paper is to report results on fabrication, structural, morphological and performance characteristics of novel TiO2/PS/Si, Au/TiO2/PS/Si and Au/PS/Si direct ammonia fuel cells (DAFC) using nanoporous silicon (PS) as proton conducting membrane (instead of traditional polymer Nafion membrane) and TiO2, Au/TiO2 or Au as catalyst layer. Porous silicon layers have been prepared by electrochemical modification of silicon substrates. Films containing titanium dioxide are more efficient catalysts for hydrogen production from ammonia solution. The Au/ TiO2/PS/Si cell exhibited the open circuit voltage 0.87 V and performance of 1.6 mW/cm2 with 50% ammonia solution as fuel at room temperature. Mechanisms of proton transport in nanoporous silicon membrane and generation of electricity in DAFC have been considered. Advantages of investigated direct ammonia fuel cells consist in simplicity of fabrication technology, which can be integrated into standard silicon micro fabrication processes and operation of cells at room temperature. The work demonstrates that the PS based fuel cells have potential for portable applications.
