Nano-sphere surface arrays based on GaAs solar cells

In this paper,we present our efforts on simulating and analyzing the effect of two-dimensional nano-sphere surface array on the characteristic of GaAs solar cells.Based on the scattering and diffraction theory of the photonic crystals,the simulation results show that the distance of adjacent nano-spheres(D)has the pronounced influence on the conversion efficiency and exhibits much poor tolerance,the absolutely conversion efficiency is reduced by exceeding of 2%as the D varies from 0 to 1μm,in addition,the lower conversion efficiency(<18%)is exhibited and almost remains unaltered when the D is of>2μm.The radius(R)of nano-spheres demonstrates much great tolerance.For D=0,the solar cells exhibit high conversion efficiency(>20%)and the efficiency is only varied by less than 1%when R is varied in a very wide region of 0.3-1.2μm.One can also find out that there is good tolerance for efficiency around the optimal value of refractive index and there is only about 0.2%decrease in final cell efficiency for around±24%variation in the optimal values,which implys that it does not demand high precision processing equipment and the whole nano-sphere array could be fully complemented using self-assembled chemical methods.

Effects of 50keV and 100keV Proton Irradiation on GaInP/GaAs/Ge Triple-Junction Solar Cells

GaInP/GaAs/Ge triple-junction solar cells were irradiated with 50 keV and 100 keV protons at fluences of 5 × 10^10 cm^-2, 1 × 10^11 cm^-2,1 × 10^12 cm^-2, and 1 × 10^13 cm^-2. Their performance degradation is analyzed using current-voltage characteristics and spectral response measurements, and then the changes in Isc, Voc, Pmax and the spectral response of the cells are observed as functions of proton irradiation fluence and energy. The results show that the spectral response of the top cell degrades more significantly than that of the middle cell, and 100 keV proton-induced degradation rates of Isc, Voc and Pmax are larger compared with 50 keV proton irradiation.

Radiation Damage Analysis of Individual Subcells for GaInP/GaAs/Ge Solar Cells Using Photoluminescence Measurements

The radiation damage of three individual subcells for GalnP/GaAs//Ge triple-junction solar cells irradiated with electrons and protons is investigated using photoluminescence （PL） measurements. The PL spectra of each subcell are obtained using different excitation lasers. The PL intensity has a fast degradation after irradiation, and decreases as the displacement damage dose increases. Furthermore, the normalized PL intensity varying with the displacement damage dose is analyzed in detail, and then the lifetime damage coefficients of the recombination centers for GaInP top-cell, GaAs mid-cell and Ge bottom-cell of the triple-junction solar cells are determined from the PL radiative efficiency.

Direct Observation of Carrier Transportation Process in InGaAs/GaAs Multiple Quantum Wells Used for Solar Cells and Photodetectors

The resonant excitation is used to generate photo-excited carriers in quantum wells to observe the process of the carriers transportation by comparing the photoluminescence results between quantum wells with and without a p-n junction. It is observed directly in experiment that most of the photo-excited carriers in quantum wells with a p-n junction escape from quantum wells and form photoeurrent rather than relax to the ground state of the quantum wells. The photo absorption coei^cient of multiple quantum wells is also enhanced by a p-n junction. The results pave a novel way for solar cells and photodetectors making use of low-dimensional structure.

Optimization of Multi-layer AR Coatings for GaInP/GaAs Tandem Solar Cells

The AR coatings for GaInP/GaAs tandem solar cell are simulated.Results show that,under the condition of the lack of suitable encapsulation, a very low energy loss could be reached on MgF2/ZnS system; in the case of glass encapsulation,the Al2O3/ZrO2 and Al2O3/TiO2 systems are appropriate choice; for AlInP window layer,the thickness of 30 nm is suitable.

GaInP/GaAs tandem solar cells with highly Te- and Mg-doped GaAs tunnel junctions grown by MBE

We report a GaInP/GaAs tandem solar cell with a novel GaAs tunnel junction（TJ） with using tellurium（Te） and magnesium（Mg） as n- and p-type dopants via dual-filament low temperature effusion cells grown by molecular beam epitaxy（MBE） at low temperature. The test Te/Mg-doped GaAs TJ shows a peak current density of 21 A/cm2. The tandem solar cell by the Te/Mg TJ shows a short-circuit current density of 12 m A/cm2, but a low open-circuit voltage range of1.4 V^1.71 V under AM1.5 illumination. The secondary ion mass spectroscopy（SIMS） analysis reveals that the Te doping is unexpectedly high and its doping profile extends to the Mg doping region, thus possibly resulting in a less abrupt junction with no tunneling carriers effectively. Furthermore, the tunneling interface shifts from the intended Ga As n＋＋/p＋＋junction to the AlGaInP/GaAs junction with a higher bandgap AlGaInP tunneling layers, thereby reducing the tunneling peak. The Te concentration of ~ 2.5 × 1020 in GaAs could cause a lattice strain of 10-3 in magnitude and thus a surface roughening,which also negatively influences the subsequent growth of the top subcell and the GaAs contacting layers. The doping features of Te and Mg are discussed to understand the photovoltaic response of the studied tandem cell.

Photoluminescence Analysis of Injection-Enhanced Annealing of Electron Irradiation-Induced Defects in GaAs Middle Cells for Triple-Junction Solar Cells

Photolumineseenee measurements are carried out to investigate the injection-enhanced annealing behavior of electron radiation-induced defects in a GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells which are irradiated by 1.8 MeV with a fluence of i ~ 1015 cm-2. Minority-carrier injection under forward bias is observed to enhance the defect annealing in the GaAs middle cell, and the removal rate of the defect is determined with photoluminescenee radiative efficiency recovery. Furthermore, the injection-enhanced defect removal rates obey a simple Arrhenius law. Therefore, the annealing activation energy is acquired and is equal to 0.58eV. Finally, in comparison of the annealing activation energies, the E5 defect is identified as a primary non-radiative recombination center.

High-power microwaves response characteristics of silicon and GaAs solar cells

The high-power microwave(HPM)effect heats solar cells,which is an important component of a satellite.This creates a serious reliability problem and affects the normal operation of a satellite.In this paper,the different HPM response characteristics of two kinds of solar cells are comparatively researched by simulation.The results show that there are similarities and differences in hot spot distribution and damage mechanisms between both kinds of solar cell,which are related to the amplitude of HPM.In addition,the duty cycle of repetition frequency contributes more to the temperature accumulation of the solar cells than the carrier frequency.These results will help future research of damage assessment technology,reliability enhancement and the selection of materials for solar cells.

Photoluminescence Analysis of Electron Damage for Minority Carrier Diffusion Length in GaInP/GaAs/Ge Triple-Junction Solar Cells

Photoluminescence（PL） measurements are carried out to investigate the degradation of GaInP top cell and GaAs middle cell for GaInP/GaAs/Ge triple-junction solar cells irradiated with 1.0, 1.8 and 11.5 MeV electrons with fluences ranging up to 3 × 10^15, 1 × 10^15 and 3 × 10^14 cm^-2, respectively. The degradation rates of PL intensity increase with the electron fluence and energy. Furthermore, the damage coefficient of minority carrier diffusion length is estimated by the PL radiative efficiency. The damage coefficient increases with the electron energy. The relation of damage coefficient to electron energy is discussed with the non-ionizing energy loss（NIEL）, which shows a quadratic dependence between damage coefficient and NIEL.

GaInP/GaAs/Ge三结太阳电池100 MeV质子位移辐照损伤效应实验研究

GaInP/GaAs/Ge三结太阳电池是当前航天器空间电源系统的核心元器件,其在空间辐射环境中遭受的辐照损伤会导致太阳电池性能参数衰降,甚至导致航天器供电系统功能失效。为获取GaInP/GaAs/Ge三结太阳电池高能质子辐照损伤退化规律,以国产GaInP/GaAs/Ge三结太阳电池为研究对象,通过开展100 MeV质子不同注量下的辐照实验,分析质子位移损伤诱发GaInP/GaAs/Ge三结太阳电池的开路电压(V_(oc))、短路电流(I_(sc))、最大输出功率(P_(m))、光电转换效率(E_(ff))等辐射敏感参数的退化规律和损伤机理。结果表明:注量范围为1×10^(11)~2×10^(12)cm^(-2)时,V_(oc)、I_(sc)、P_(m)、E_(ff)的退化程度随辐照注量的增加而增大,当注量为2×10^(12)cm^(-2)时,P_(m)和E_(ff)归一化处理后的退化程度均为16.88%,与V_(oc)和I_(sc)相比,衰减更严重。对不同注量辐照所得V_(oc)、I_(sc)、P_(m)、E_(ff)进行拟合,获得了V_(oc)、I_(sc)、P_(m)、E_(ff)随辐照注量变化的特征曲线,根据该曲线可预估GaInP/GaAs/Ge三结太阳电池不同注量下性能的衰减幅度。

质子辐照下三结GaAs太阳电池性能衰退分析

在构建三结GaAs太阳电池模型的基础上,模拟分析不同能量质子辐照下中电池GaAs的性能衰退,对三结GaAs电池在轨服役评估具有重要意义。结合质子与电池靶材发生的相互作用,建立一种将微观损伤机理与宏观电池性能变化相结合的电池辐照损伤评价方法。结果表明,在三结GaAs太阳电池中,40 keV能量的质子辐照对中电池的影响最小;100和150 keV能量的质子辐照主要对中电池基区造成影响,导致电池性能一定程度上的衰退;70 keV能量的质子辐照对于中电池结区的影响最大,从而导致量子效率QE和并联电阻Rsh的变化最为明显。

空间用GaInP/GaAs/Ge太阳电池栅线仿真

准确的仿真模型是设计太阳电池栅线的关键。从受光面发热损失、细栅遮挡损失、细栅发热损失入手,建立了空间用GaInP/GaAs/Ge太阳电池栅线仿真模型。设计了以表面薄层电阻、细栅形状、细栅间距为变量的验证实验,制备的样品效率与仿真预计效率吻合良好。应用栅线模型在两种类型的3 cm×4 cm尺寸空间用GaInP/GaAs/Ge太阳电池进行栅线优化,两种太阳电池经优化后转换效率分别提升了0.19%和0.29%,证明该栅线设计模型准确,应用效果良好。

GaInP/GaAs太阳电池的柔性封装及稳定性

柔性Ⅲ-Ⅴ薄膜太阳电池通常被作为空间电源在航天器上使用,而在实际应用中适宜的封装材料可以保护电池免受水分、氧化、污染物等环境因素的影响.因此,探究合适的柔性封装方案和电池性能的长期稳定性至关重要.本文利用电阻焊方法将制备好的柔性双结GaInP/GaAs太阳电池进行焊接,之后采用具有高透光性的薄膜材料和热熔胶与柔性电池进行层压封装并研究了其在恶劣储存条件下的性能稳定性和环境耐受性.研究结果表明,柔性封装太阳电池在1000 h以上的温度为85℃,相对湿度85%(85℃/85%RH)的湿热试验以及108次温度范围为-60℃-75℃的冷热循环老化试验后仍然保持了很好的稳定性,表明封装工艺对柔性太阳电池具有较好的保护作用.此外,基于二极管模型的电学仿真结果表明,柔性封装后电池性能的改变是由于载流子复合增强,从而降低了开路电压.

Al_xGa_(1-x)As/GaAs太阳电池MgF_2/ZnS双层减反射膜的研究

介绍了在 Al Ga As/ Ga As太阳电池上制备 Mg F2 / Zn S双层减反射膜的研究工作。引入了有效反射率 Re,并通过使 Re 极小来实现减反射膜的优化设计 ,考虑了 Mg F2 / Zn S双层减反射膜与窗口层的耦合。实验上获得了良好的减反射膜 ,提高了 Al Ga As/ Ga As太阳电池的短路电流和效率 ,表明用Re极小化来设计减反射膜是合理的。

单晶Si、单结GaAs太阳能电池的激光损伤特性对比研究

采用1064 nm纳秒脉冲激光辐照单晶Si、单结G As太阳能电池,针对不同强度激光辐照太阳能电池的损伤特性进行了实验研究,得出激光光斑聚焦在电池栅线上时,电池更易损伤,单晶Si电池的栅线打断之后仍能很好工作,单结GaAs电池却完全失效,这是由于高掺杂的基底锗熔融凝固连接栅线,导通电池正负极.实验结果还表明,激光辐照在电池表面时,对单晶Si电池基本没有影响,而GaAs电池输出性能也没有很大幅度的下降.理论分析了纳秒激光对电池的损伤主要是热、力效应共同作用的结果.热效应使材料熔化、气化,力效应主要沿着激光传输的方向,垂直于材料表面.常温下Si材料对1 064 nm有较强的本征吸收,GaAs电池的GaAs层透过1 064 nm,Ge基底本征吸收1 064 nm,Ge材料的熔点低于Si材料且其禁带宽度更窄,故其初始损伤阈值略低.通过SEM扫描电镜、激光拉曼材料分析及X射线光电子能谱仪等分析手段对实验结果进行了验证.

GaAs基Ⅲ-Ⅴ族多结太阳电池技术研究进展

GaAs太阳电池由于其性能优越,成为了光伏领域的发展重点。简单介绍了GaAs基Ⅲ-Ⅴ族多结太阳电池的应用和研究进展,并对其发展趋势进行了展望。

空间实用背场Si太阳电池和GaAs/Ge太阳电池性能随质子辐照注量变化的比较

研究了空间实用背场 Si太阳电池和 Ga As/ Ge太阳电池性能随质子辐照注量 1× 10 9～ 5× 10 1 3cm- 2 的变化 .实验表明 ,两种太阳电池的电性能随辐照注量增加有不同的衰降趋势 .背场 Si太阳电池性能参数 Isc、Voc和 Pmax衰降变化快 ,辐照注量为 2× 10 1 0 cm- 2时 ,Pmax就已衰降为原值的 75 % ;而 Ga As/ Ge电池对应相同的衰降辐照注量达 8× 10 1 1 cm- 2 ,且其 Isc、 Voc和 Pmax衰降变化起初缓慢 ,当辐照注量接近 3× 10 1 2 cm- 2 时才迅速下降 .背场 Si电池和 Ga As/ Ge电池性能衰降分别与质子辐照引入的 Ev+0 .14 e V及 Ev+0 .4 3e V和 Ec- 0 .4 1e

GaInP_2/GaAs/Ge叠层太阳电池材料的低压MOCVD外延生长

本文采用自制的 L P-MOCVD设备 ,外延生长出 Ga In P2 / Ga As/ Ge叠层太阳电池结构片 ,对电池材料进行了 X射线衍射测试分析 .另外 ,采用二次离子质谱仪测试了电池结构的剖面曲线 .用此材料做出的叠层太阳电池 ,AMO条件下光电转换效率 η=1 3 .6% ,开路电压 Voc=2 2 3 0 m V,短路电流密度 Jsc=1 2 .6m A/ cm2 .

质子辐照与电子辐照对空间GaAs/Ge太阳电池性能影响比较

利用地面实验室加速器提供的离子束模拟空间质子、电子辐射,分别对空间实用GaAs/Ge太阳电池进行不同注量的辐照,并跟踪测试其电性能变化和深能级瞬态谱,研究这种太阳电池的电性能参数随质子、电子辐照注量的变化关系,得到质子、电子辐射效应及两者辐射效应的联系规律.结果表明:引起电池性能参数衰降相同时,1 MeV电子辐照注量比10 MeV质子的通常要大3个量级,质子辐照与电子辐照使电池性能参数Pmax下降了25%时,辐照注量有近似关系Φ1 MeV(e)≈2 500×Φ10 MeV(p).10 MeV,3×1012cm-2质子辐照在电池材料中引入Ec-0.18 eV和Ec-0.65 eV深能级,1 MeV,1×1015cm-2电子辐照在电池材料中引入Ec-0.12 eV和Ec-0.18 eV深能级,电子、质子辐照产生的损伤缺陷不尽相同.

国产高效GaInP/GaAs/Ge三结太阳电池的低能质子辐射效应

运用2×1.7MV串列静电加速器提供的质子束,对MOCVD方法制备的GaInP/GaAs/Ge三结电池进行低能质子辐射效应研究.选质子能量为0.28,0.62和2.80MeV,辐照注量为1×1010,1×1011,1×1012和1×1013cm-2.对电池的辐射效应用I-V特性和光谱响应测试进行分析.研究结果表明:随辐照注量的增加,太阳电池性能参数Isc,Voc和Pmax的衰降幅度均增大;但随质子辐照能量的增加,Isc,Voc和Pmax的衰降幅度均减小.实验中0.28MeV质子辐照引起电池Isc,Voc,Pmax衰降最显著,三结电池中光谱响应衰降最明显的是中间GaAs电池.