键合集成AlGaInP/GaAs/InGaAsP/InGaAs太阳电池组分与厚度对效率的影响

寻找比传统晶格匹配GaInP/InGaAs/Ge结构具有很高效率的高效太阳电池体系是目前高效太阳电池研究重点。基于直接键合集成技术的AlzGa1-zInP/GaAs/In1-xGaxAsyP1-y/InGaAs四结太阳电池是一条有效的途径。该结构中In-GaAsP材料光学带隙可以在0.75～1.35 eV之间连续调节。作为一种新结构,一些关键点还是不清楚,比如考虑材料吸收系数与实际厚度限制下的带隙优化组合,子电池厚度与最高效率之间的耦合影响等,这些都对结构设计提出了新的挑战。采用半经验全局优化工具,研究了InGaAsP子电池组分和吸收系数比较小的InGaAs子电池厚度这两个因素对最高效率的影响,并对器件设计给出了一些方向性意见。     

量子阱结构对GaInP/Ga(In)As/Ge电池的光谱响应改善

采用MOCVD工艺制备具有应变平衡量子阱结构GaInP/Ga(In)As/Ge三结太阳电池的方法,及量子阱结构对中间电池的光谱响应的改善,从而使GaInP/Ga(In)As/Ge三结太阳电池各子电池电流匹配设计更为合理,揭示了量子阱结构提高GaInP/Ga(In)As/Ge三结级联太阳电池光电转换效率的可能性。     

32％效率三结砷化镓太阳电池设计与在轨应用

采用晶格小失配的GaInP/GaInAs/Ge三结砷化镓太阳电池结构,通过增加顶电池与中电池中In组分,选取带隙组合为1.87 eV/1.35 eV/0.67 eV的结构体系,使顶、中电池光吸收下限分别红移15和40 nm左右,提高了三结砷化镓太阳电池的电流密度,提升了太阳电池光电转换效率,研制出平均光电转换效率为32%(AM0,25℃)的三结砷化镓太阳电池。该太阳电池已成功应用于PakTES-1A卫星太阳电池阵,入轨初期由其SG1与SG5子阵在轨电流数据计算对比地面同工况测试结果,差异仅为-0.2%和0.5%。产品可用于后续航天器高效率太阳电池阵。     

含有布拉格反射器的GaInP/GaInAs/Ge太阳电池研究

通过数学方法,对中心波长为880 nm的布拉格反射器进行了理论计算和设计。采用MOCVD技术在Ge衬底上外延生长了15个周期,中心波长为880 nm的AlAs/GaAs结构的布拉格反射器,并且成功植入到GaInP/GaInAs/Ge结构的太阳电池中,使中间电池减薄到1.5μm,并且在AM0光谱下电池效率达到29.36%。     

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。     

超薄GaInP/GaInAs/Ge太阳电池研究

通过特殊的MOCVD技术和器件工艺,应用超薄衬底和对正常衬底的减薄两种方法,成功地制作出了80 mm厚的超薄GaInP/GaInAs/Ge结构的太阳电池。对太阳电池进行了相关的测试,并对实验结果进行了分析和讨论。     

残留应变对晶格失配太阳电池设计的影响

由于晶格失配太阳电池中存在残留应变,1.0eV InGaAs子电池和0.7eV InGaAs子电池的带隙不再固定地对应于单一In组份,而是与In组份和残留应变都有关系。从实验和理论上研究了残留应变对晶格失配太阳电池带隙的影响,计算了不同应变和组份的InGaAs电池的等带隙分布线,并讨论了残留应变对晶格失配太阳电池设计的影响。     

MOCVD制备禁带宽度2.1～2.2 eV的AlGaInP太阳电池

禁带宽度2.0~2.2 eV的AlGaInP太阳电池是制备五至六结叠层太阳电池必需的一结子电池,但目前高质量高Al组分的AlGaInP材料制备仍存在不小的挑战。采用金属有机化学气相沉积(MOCVD)设备制备了禁带宽度2.1~2.2 eV的AlGaInP太阳电池,研究了外延生长温度、表面活性剂等外延和结构参数对AlGaInP材料和电池性能的影响。通过优化外延生长温度和掺入表面活性剂,获得了在AM0光谱下开路电压达到1.58 V、光电转换效率为12.48%的AlGaInP单结太阳电池。     

基于台阶刻蚀工艺的GaInP/GaAs/Ge太阳电池激光划片研究

通过湿法台阶刻蚀工艺,在GaInP/GaAs/Ge太阳电池晶圆上按设计尺寸做成切割槽,继而采用皮秒或纳秒激光划切晶圆衬底,完成尺寸误差低于10μm的电池切割,该工艺制备的太阳电池性能与金刚石砂轮划片效果等同。和金刚石砂轮划片工艺相比,激光划片具有速度快、切割图形多样、维护周期短等优点。     

a-Si(p)/c-Si(n)异质结太阳电池的AFORS-HET模拟优化

采用限定变量的方法,运用AFORS-HET(Automat FOR Simulation of HETerostructures)软件计算模拟了不同厚度、掺杂浓度和禁带宽度的非晶硅薄膜背场以及不同厚度、禁带宽度的非晶硅本征层对a-Si(p)/c-Si(n)异质结太阳电池的影响.结果表明,在其它参数不变的情况下,增加较薄的背场和中间本征层,可以提高太阳电池的整体性能,其光电转换有很大程度提高,其最高转换效率可达20.75％;其中,中间本征层在厚度不超过20 nm时,对电池的短路电流影响不大,而其它性能则相对下降;当非晶硅薄膜背场的掺杂浓度为1019 cm-3以上,带隙为1.7 eV,厚度为5 nm时,电池性能最佳.     

Optimization of 635-nm tensile strained GaInP laser diodes

The authors measure the combined affect of strain and well width on the gain and recombination mechanisms in 635-nm laser structures containing three combinations of tensile strain and well width of 0.5%/10 nm, 0.6%/12.5nm, and 0.7%/15nm using the segmented contact method. They find an improvement in the intrinsic properties with increasing strain but the dominant effect in device performance is an extrinsic effect-the overall radiative efficiency, which is found to be less than 30% for all three samples even at 200 K. The authors attribute this to nonradiative recombination within the quantum well. The intrinsic gain-spontaneous current density characteristics of all three samples exhibit similar tangential gain parameters and a decreasing transparency current density from 116 to 87 to 83 Acm/sup -2/ with increasing strain and well width. They show that the reduction occurs because of a reduction in the TE polarized spontaneous recombination due to the increased splitting of light and heavy hole subbands. The quasi-Fermi level separation required to achieve a fixed value of gain is insensitive to the particular strain/well width combination. The authors use a microscopic laser theory to model the behavior of a larger range of combinations of tensile strain and well width than were examined experimentally, having first demonstrated that the model correctly describes the experimental gain spectra of the only sample exhibiting appreciable gain in both TM and TE polarizations. The calculated data suggest that using still larger values of strain and well width produces no further benefit in performance.     

The impact of LOC structures on 670-nm (Al)GaInP high-power lasers

We investigate the potential of large optical cavity (LOC)-laser structures for AlGaInP high-power lasers. For that we study large series of broad area lasers with varying waveguide widths to obtain statistically relevant data. We study in detail I/sub th/, /spl alpha//sub i/, /spl eta//sub i/, and P/sub max/, and analyze above-threshold behavior including temperature stability and leakage current. We got as expected for LOC structures minimal /spl alpha//sub i//spl les/1 cm/sup -1/ resulting in /spl eta//sup d/=1.1 W/A for 64/spl times/2000 /spl mu/m/sup 2/ uncoated devices. We obtain total output powers /spl ges/3.2 W (qCW) and /spl ges/1.5 W (CW) at 20/spl deg/C.     

Thermal analysis of multi‐finger GaInP collector‐up heterojunction bipolar transistors with miniature heat‐dissipation packaging structures

We build up a finite element modeling (FEM) approach to analyze the thermal performance of collector‐up (C‐up) heterojunction bipolar transistor (HBTs) with a heat‐dissipation via configuration. Highly compact heat‐dissipation packaging structures of GaInP/GaAs C‐up HBTs have been designed and evaluated systematically. In this work, we devise the 2‐D and 3‐D models to simulate the actual devices and to investigate the temperature distribution behavior. Results from 2‐D model indicate that the large heat‐dissipation via configuration can be further reduced by 29% to meet the requirement of HBT‐based small high‐power amplifiers (HPAs) for the cellular phones. Furthermore, the demonstrated results show that the maximum temperature within the collector calculated from 3‐D model is lower than that from 2‐D model. In the 3‐D analysis, it is revealed that the configuration can be reduced by 32%. Therefore, thinning the heat‐dissipation via constructed underneath the GaInP/GaAs C‐up HBT should be helpful for miniaturization of HBT‐based HPAs in future mobile communication systems. Copyright © 2009 John Wiley & Sons, Ltd.     

混合动力电动车用高效双向直流变换器的设计

针对传统以蓄电池为动力的电动车存在的问题,提出以超级电容加双向DC-DC变换器为辅助动力源的方案。该方案在弥补蓄电池缺陷的同时,提高了整个系统的能源利用效率,并增加了电动车的续驶里程。在简要介绍了超级电容储能系统的基础上,主要研究和设计了系统中的核心部件—双向DC-DC变换器,分析了双向DC-DC变换器的工作模式和控制策略,并对双向变换器进行了软开关分析。Matlab仿真所得的相应波形验证了方案的有效性。     

Sn/O/H/N/C/Cl系统中锡的氧化动力学研究

控制燃煤锅炉中Sn的排放已经越来越被环境学界所关注。已有数据表明气相排放的和残留在飞灰中的Sn的变化范围很大,引起这种变化的原因还不清楚。在尾部烟道附近,Sn以元素态和二价氧化物蒸汽形式存在,已知水溶性二价锡氧化物更容易从烟气中脱除。为了更好地控制Sn的排放,必须了解燃烧过程中Sn的反应产物以及各浓度与时间的关系,即Sn的反应动力学机制,该文首次采用量子化学经典过渡态理论的方法研究了烟气中痕量元素锡的关键基元反应动力学参数,继而提出了Sn/O/H/N/C/Cl系统的氧化动力学模型。在典型的反应温度和组分浓度下进行了动力学的数值模拟,并通过敏感性分析找到了影响系统反应速率最重要的基元反应。     

Ferroelectric behaviors of sandwich structured PbZr0.52 Ti0.48O3/Pb(Mg1/3Ta2/3)0.7Ti0.3O3/PbZr0.52Ti0.48O3 thin film

Sandwich structured PbZr_0.52Ti_0.48O₃/Pb(Mg_1/3 Ta_2/3)_0.7Ti_0.3O₃/PbZr_0.52Ti_0.48O₃ (PZT/PMTT/PZT) thin films have been successfully synthesized via a combined route involving sol-gel and RF magnetron sputtering. Insertion of the PMTT interlayer effectively suppressed formation of the heterogeneous “rosette” structure of PZT thin film when deposited onto Pt/Ti/SiO₂/Si substrate. While both remanent polarization and coercive field were lowered for the sandwich structured films, the coercive field was reduced more significantly. Such sandwich structured films exhibit improved fatigue behavior and the relative permittivity can not be simply described as a series connection of individual components of perovskite layers.     

层状正极材料LiNi1/3Co1/3Mn1/3O2-xClx的合成及性能

以溶胶-凝胶法制备氯阴离子掺杂型正极材料LiNi1/3 Co1/3Mn1/3 O2-xClx(x=0、0.05、0.10和0.15).用TG/DTG测试分析了材料的相形成过程.XRD分析结果表明:在空气气氛中以850℃煅烧20 h制备的材料,具有良好的六方单相层状结构.电化学性能测试结果表明:掺杂抑制了高电压区域的相变过程,提高了材料的可逆性;x=0.10的样品具有良好的循环性能和倍率性能,在2.0～4.6V循环,0.15 C、1.00 C首次放电比容量分别为198.7 mAh/g、166.4 mAh/g,第25次0.15 C循环的放电比容量为197.9 mAh/g.