GaInP/GaAs/Ge叠层太阳电池的研制及其温度依赖性分析

利用MOCVD方法制备了GaInP/GaAs/Ge叠层太阳电池。测试了I-V特性,并测试分析了该电池性能在30℃至170℃温度范围内的变化情况。测试结果表明,随着温度的升高,短路电流密度略微增大,温度系数为9.8 (μA/cm2)/℃;开路电压以系数-5.6mV/℃急剧下降;填充因子也随之下降（-0.00063 /℃）;电池的转换效率随温度升高线性减小,温度从30℃升高至 130℃时,效率从28%下降至22.1%。最后,本文对该叠层电池随着温度变化的特性给予了详细的理论分析。     

红光GaInP/AlGaInP正方形微腔激光器

利用普通光刻和感应耦合等离子体(ICP)刻蚀技术制作了红光GaInP/AlGaInP正方形微腔激光器,光功率电流曲线表明,器件实现了200 K的低温激射。对边长为10μm、输出波导长为30μm的正方形微腔激光器,室温测量得到的纵模模式间距为1.3 nm,所对应的是由输出波导和正方形腔组成的F-P腔的F-P模式。采用二维时域有限差分法(FDTD),模拟研究了侧壁粗糙对正方形腔模式品质因子的影响。     

用于GaInP/GaAs双结叠层太阳电池的MOVPE外延材料

采用金属有机化合物气相淀积(MOVPE)技术生长用于GaInP/GaAs双结叠层太阳电池的外延材料。针对材料生长中的隧穿结、p-AlInP层等关键问题,通过对掺杂剂、生长技术及条件的调整与改进,极大地提高了GaInP/GaAs双结叠层太阳电池性能,最高转换效率达到23.8%(AMO,25℃)。     

三元合金Ga_(0.52)In_(0.48)P的时间分辨发光谱

在室温和低温液氮下 ,研究了有序和无序 Ga0 .52 In0 .4 8P的时间分辨发光谱。对实验结果的拟合表明 ,有序 Ga0 .52 In0 .4 8P的发光呈双指数规律衰退。其中快过程对应着有序区域上载流子的复合 ,慢过程则对应着有序区域和无序区域的空间分离中心上载流子的复合。无序 Ga0 .52 In0 .4 8P的发光在室温下呈单指数规律衰退。同时从低温下的时间分辨发光谱还可以看出有序样品的发光峰随着延迟时间的变长而蓝移 ,说明低温下在有序 Ga0 .52In0 .4 8P中存在着载流子从无序区域到有序区域的转移     

Effects of group V precursor and step structure on ordering in GaInP

The effects of the P precursor have been studied for GaInP layers grown at 670°C on singular (001) GaAs substrates. Use of either of the two precursors, tertiarybutylphosphine (TBP) and phosphine (PH₃), for the organometallic vapor phase epitaxial growth, has been shown to result in the same degree of CuPt order in the epitaxial layers. However, the steps on the surface are mainly bilayers, approximately 5.8Å in height, for growth using TBP and mainly monolayers for growth using PH₃. This indicates that the step structure plays no role in the ordering process occurring on the surface during growth. Examination of the spacing between these surface steps vs the input partial pressure of the P precursor indicates that neither the surface diffusion coefficient nor the sticking coefficients of group III adatoms at the step edge is dependent on the P precursor. This suggests that the step structure also has no effect on the sticking coefficient.     

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 30nm is suitable.     

Electrical properties of He+ ion-implanted GaInP

The electrical properties of high resistivity GaInP layers produced by He⁺ ion implantation have been studied. Thick high-resistivity layers (ρ > 10⁷ Ω-cm) were obtained using multi-energy implants (80 keV, 120 keV, and 150 keV). Current-voltage (I-V) measurements of mesa diodes with two ohmic contacts indicate that in the temperature range from 200 to 300K, the dominant current flow mechanism in both n-type and p-type implanted materials is Poole-Frenkel emission, especially in the range of high electric field (>10⁵ V/cm). The thermal activation energy E_a and the potential barrier height Φ_o of the generated deep levels are 0.16±0.005 eV and 0.33±0.005 eV, respectively. At low temperature, the hopping current dominates at low and moderate applied electric fields, and the I-V curves show an ohmic characteristic. The high-temperature annealing behavior of the implanted GaInP indicates that the compensation of free carriers in the material is dominated by damage-related levels, which are annealed out at high temperatures. In regard to typical alloying cycles of metal contacts in device fabrication, it is worth noting that the resistivity is still as high as 2 × 10⁸ Ω-cm for n-type samples (5 × 10⁷ Ω-cm for p-type) after 350°C annealing, which suggests that multi-energy He⁺ implantation is suitable for implant isolation in the GaInP device technology.     

AlGaInP/GaInP多量子阱的拉曼光谱

利用LP-MOCVD生长了不同周期的AlGaInP／GaInPMQW样品，并测量了它们的拉曼光谱。由于样品包括了掺杂的电流扩展层和欧姆接触层以及上、下限制层，拉曼光谱中观察到了与掺杂有关的耦合电子(空穴)气-纵光学声子模。根据喇曼光谱的选择定则，结合光致发光谱，发现AIP-LO／TO的相对强度比可以评定晶体AlGaInP MQW的生长质量。     

Optimizing back surface field for improving Voc of(Al)GaInP solar cell

GaInP and AlGaInP solar cells were grown by metal organic chemical vapor deposition (MOCVD), and theoretical analysis demonstrated that hetero-interface recombination velocity plays an important role in the optimizing of cell performance, especially the interface between base layer and back surface field (BSF). Measurements including lattice-matched growth and pseudo-BSF were taken to optimize BSF design. Significant improvement of V_oc in GaInP and AlGaInP solar cells imply that the measures we took are effective and promising for performance improvement in the next generation high efficiency solar cells.     

低压金属有机化合物气相外延生长的 (Al_x Ga_(1-x))_(0 .5 1)In_(0 .49)P折射率测量(英文)

采用测量反射谱方法确定了低压金属有机化合物气相外延生长的与 Ga As衬底匹配 (Alx Ga1 - x) 0 .5 1 In0 .49P外延材料的折射率 .实验中测量的反射谱波长范围为 0 .5— 2 .5 μm.在拟合实验数据过程中采用了单振子模型 .折射率数据用于分析应变量子阱 Ga In P/ Al Ga In P可见光激光二极管波导 ,计算出的器件远场图与实验数据吻合很好 .