激光无线能量传输效率的实验研究

为了提高激光无线能量传输系统的转换效率,基于单结GaAs光电池的工作原理,用调节照射光电池的激光参量的方法,从理论上对激光无线能量传输系统的有关部分进行了优化设计,并通过实验研究了激光波长、激光强度等因素对光电池能量转换效率的影响。结果表明,单结GaAs光电池对单色激光的光电转换效率远高于传统的单晶硅电池,最高转化效率可达61.2%。该结果对于激光无线能量传输技术的应用具有一定参考价值。     

纳秒激光与硅电池片光电转换效率变化及机理初步分析

描述了用6 ns波长为1 064 nm的激光在SF6中作用于硅表面产生的锥形微观结构过程,测试了经激光处理及未经激光处理之硅晶片制成的硅电池光电转换效率的变化。实验显示,激光处理后的晶片所制电池其光电转换效率提高,其增加量为未经激光处理的电池效率的10%~15%,对这种变化进行了初步机理分析,认为可能与硅逾量电子结合能和Fermi能级有关。激光处理硅晶片的应用,也会进一步改善硅电池制作工艺。     

光强均匀度与标准粒子信号分布关系研究

为了研究光敏区光强分布对粒子计数器标准粒子信号分布的影响,从理论上分析了光敏区光强概率分布和标准粒子信号幅度概率分布之间的关系,并建立了能统一描述光敏区光强分布均匀度和信号幅度分布均匀度的数学模型,此模型定量分析了光敏区光强均匀度对信号分布曲线的影响,同时也揭示了长期制约国产粒子计数器分辨能力的本质因素,并给出了实验验证.理论和实验结果表明,光敏区光强分布的不均匀性是影响计数器分辨能力的主要因素.     

GaAs量子阱太阳能电池转换效率的计算

采用细致平衡模型计算了GaAs量子阱太阳能电池的转换效率,同时对量子阱结构带来的几种效应,如准费米能级分离、热载流子效应等进行了分析,并将碰撞离化效应引入此细致平衡模型中,通过计算研究了其对量子阱太阳能电池转换效率的影响.结果表明碰撞离化效应可以提高电池的转换效率,但提高幅度有限.     

GaAs量子阱太阳能电池转换效率的计算

采用细致平衡模型计算了GaAs量子阱太阳能电池的转换效率,同时对量子阱结构带来的几种效应,如准费米能级分离、热载流子效应等进行了分析,并将碰撞离化效应引入此细致平衡模型中,通过计算研究了其对量子阱太阳能电池转换效率的影响.结果表明碰撞离化效应可以提高电池的转换效率,但提高幅度有限.     

三结GaAs电池损伤对输出特性的影响研究

针对发生损伤后三结GaAs电池的电学特性进行了研究。从三结电池的等效电路模型出发,根据光伏效应相关理论,建立了GaAs三结电池损伤分析模型,具体计算了损伤发生在不同位置时,光电池输出电压、功率、效率的变化。结果表明,顶结发生热熔损伤对电池的电学特性影响最大,将直接导致光电转换效率下降17.23%。中结发生热熔损伤对电池的电学特性影响次之,将引起4.23%的效率下降。底结损伤对电池的电学特性影响相对最小,所导致的光电转换效率下降量为2.42%。     

变掺杂GaAs光电阴极吸收系数的表征

确定阴极材料的光子吸收系数,是开展变掺杂GaAs光电阴极光电发射性能理论研究的重要条件之一。分析了变掺杂阴极的结构特点,提出了材料等效光子吸收系数的概念,并给出了等效光子吸收系数的计算方法。设计了变掺杂阴极样品并进行了阴极Cs、O激活实验,理论计算了材料的等效光子吸收系数并对激活后的阴极量子效率进行了拟合仿真,拟合曲线同实验曲线非常一致,证明了该计算方法的有效性。     

GaAs基量子阱谐振腔增强型光电探测器特性研究

通过对谐振腔增强型(RCE)光电探测器的理论分析和实验测试结果,证明对应不同光束入射角度,RCE光电探测器的模式波长按一定规律可调谐.并给出当入射角度变化10°～60°,模式调谐范围约为40nm,而谐振波长处的量子效率峰值及半高宽FWHM的变化与材料吸收系数紧密相关.     

GaAs基量子阱谐振腔增强型光电探测器特性研究

通过对谐振腔增强型（RCE）光电探测器的理论分析和实验测试结果，证明对应不同光束入射角度， RCE光电探测器的模式波长按一定规律可调谐. 并给出当入射角度变化10°～60° ，模式调谐范围约为40nm，而谐振波长处的量子效率峰值及半高宽FWHM的变化与材料吸收系数紧密相关.     

GaAs基量子阱谐振腔增强型光电探测器特性研究

通过对谐振腔增强型(RCE)光电探测器的理论分析和实验测试结果,证明对应不同光束入射角度,RCE光电探测器的模式波长按一定规律可调谐.并给出当入射角度变化10°～60°,模式调谐范围约为40nm,而谐振波长处的量子效率峰值及半高宽FWHM的变化与材料吸收系数紧密相关.     

Effect of the electric field in the space-charge layer on the efficiency of short-wave photoelectric conversion in GaAs Schottky diodes

A study is reported of the quantum efficiency of the short-wave photoelectric effect as function of the reverse bias applied to GaAs Schottky diodes when the light absorption length is much shorter than the width of the space charge region. The quantum efficiency of photoelectric conversion is found to depend strongly on the contact electric field and the photon energy. The field independence of the quantum efficiency is interpreted in terms of a fluctuational trap model. The model can also be used to determine the loss factor for hot photocarriers, which is found to increase in a stepwise manner with increasing photon energy. This effect is explained in terms of the formation of excitons in X-and L-valleys of the semiconductor. Fiz. Tekh. Poluprovodn. 31, 1225–1229 (October 1997)     

Problems of efficiency of photoelectric conversion in thin-film CdS/CdTe solar cells

The available data are generalized and new results of investigation of losses of photoelectric energy conversion in CdS/CdTe thin-film solar cells are reported. The requirements concerning the electrical characteristics of the material, for minimizing the electric losses and providing effective radiation absorption in the active region of the diode structure, are discussed and refined. It is shown to what extent the incomplete collection of photogenerated charge carriers is determined by recombination both at the CdS/CdTe interface (based on the continuity equation taking into account the surface recombination) and in the space-charge region (based on the Hecht equation). The comparison of the calculated and experimental results shows that, in general, both types of recombination losses are important but can be virtually eliminated by the choice of parameters of both the barrier structure and the material used. The limiting values of the short-circuit current density and efficiency of the CdS/CdTe solar cell are discussed.     

Effect of illumination uniformity on GaAs photoconductive switches

The dynamic behavior of a GaAs photoconductive switch was studied with an electro-optic imaging system during the first 2 ns after optical illumination. The switch behavior changed as a function of the spatial distribution of the optical illumination. Symmetric and asymmetric illumination schemes were investigated experimentally with our electro-optic imaging system. The electric fields were significantly enhanced in the regions of low photo-carrier density. Approximately 1 ns after illumination the simple longitudinal variation of the electric field gave way to nonuniform transverse structure. The experimental results were modeled by treating the switch as an integral part of a transmission line consisting of discrete elements. The experimental results matched the predictions of the transmission-line model in terms of the electric-field enhancements and efficiency     

激光辐照下光电电池的极限能量转化效率研究

采用激光输能技术解决临近空间飞行器的能源供给问题的研究正在广泛开展。为研究激光辐照下的光电电池的极限性能,基于细致平衡理论,分析了激光辐照条件下光电材料禁带宽度与最佳激光波长的关系,得到了光电电池各类输出性能参数的计算方法。通过计算,得到了激光波长、激光功率密度和电池温度对能量转化效率等参数的影响规律。结果表明对于特定材料的光电电池存在最佳的激光波长使其获得极限能量转化效率;激光功率密度的增加可以提高光电电池的能量转化效率,但达到一定数值后提高不再明显;对于电池温度的影响,不同的输出性能参数具有不同的温度系数。     

Limiting photovoltaic monochromatic light conversion efficiency

Notwithstanding the relatively low energy conversion efficiencies typical of standard solar photovoltaic systems, photovoltaic cells are shown, in principle, to be capable of converting well‐collimated monochromatic light at efficiencies arbitrarily close to 100%. To approach such efficiencies, radiative recombination must be the main recombination process within the cell. The intensity of the monochromatic light must be high, and the cell should be designed so that it does not absorb or emit light outside the range of angles and wavelengths required to accept the incident monochromatic light. The thermodynamic basis of such high efficiency is also briefly discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

基于压频变换的光强检测仪的设计

提出了一种以单片机STC12C2052为控制核心的基于压频变换器的光强检测仪的制作,功能是快速准确地将所测量光的强度以数据的形式通过PC显示器显示出来。光照度检测仪系统主要包括四部分:光电转换及信号处理电路,压频变换电路,STC12C2052控制器,光亮度显示模块。除了介绍系统的硬件构成,还涉及软件程序及显示软件的调试结果。硬件电路简单、所需成本低等特点,适用于对速度要求不太高的场合。     

Improvement in the light conversion efficiency of silicon solar cells by pure hydrogen annealing

In this report, the effects of pure hydrogen gas annealing on series resistance (R_s), shunt resistance (R_sh), open circuit voltage (V_oc), short circuit current (I_sc), fill factor, and efficiency were investigated systematically using standard, commercially available polysilicon solar cells. Improvements on the electrical characteristics, fill factors, and efficiency of the solar cells were observed after annealing by pure hydrogen gas at 350 °C for 15 min. In the best case, the conversion efficiency was raised by nearly 1% point. Judging from our experimental evidences, the improvement on cell performance could be mostly attributed to the reduction of R_s and improvement in Ag grid/emitter contact resistance in the cells during the annealing process.     

红外光源参数对光电编码器信号的影响

红外发光管是光电编码器的重要组成部分,而光源参数对莫尔条纹信号的正弦性和正交性有直接影响,从而影响光电编码器的细分精度和分辨力。文中研究了其发散角、光源宽度对编码器的信号影响。首先,分析了光源对光栅信号光通量的影响,运用频域方法导出了透光特性函数;然后,分析了两种不同光源对同一码盘形成信号的影响;最后,应用Matlab仿真计算了莫尔条纹信号的对比度、正交性、正弦性。实验结果表明,使用两种不同光源的编码器精度相差达到30%,改进后的编码器高次谐波占比明显减少,信号稳定性好。因此研究光源参数对提取高质量莫尔条纹有重要意义,并为高精度编码器设计提供重要参考依据。     

激光输能光电转换增效方法研究现状

光电转换效率是激光输能技术的重要指标,如何提高光电转换效率是目前激光输能技术研究的重点。在光电转换基本原理的基础上,分析了光电转换效率的影响因素,介绍了光电转换增效方法,以期为解决光电转换效率较低问题及推进激光输能技术实用化提供参考。