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12.
Kanglin Xiong Shulong Lu Jianrong Dong Taofei Zhou Desheng Jiang Rongxin Wang Hui Yang 《Solar Energy》2010,84(12):1975-1978
There are many difficulties limiting the further development of monolithic multi-junction solar cells, such as the growth of lattice-mismatched material and the current matching constraint. As an alternative approach, the light-splitting photovoltaic system is investigated intensively in different aspects, including the energy loss mechanism and the choice of energy bandgaps of solar cells. Based on the investigation, a two-dual junction system has been implemented employing lattice-matched GaInP/GaAs and InGaAsP/InGaAs cells grown epitaxially on GaAs and InP substrates, respectively. 相似文献
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J. Garcia C. Dua S. Mohammadi J. W. Park D. Pavlidis 《Journal of Electronic Materials》1998,27(5):442-445
We report on the complete characterization of a hydride- and hydrogen-free chemical beam epitaxy (CBE) process for the realization
of GaAs/GaInP heterojunction bipolar transistors. Alternative group V sources tertiarybutylarsine, tertiarybutylphosphine,
and trisdimethylaminoarsenic are used instead of traditionally employed AsH3 and PH3. A very high degree of reproducibility of growth parameters (fluxes, substrate temperature, doping levels) is demonstrated.
Total defect densities lower than 10 def/cm2 are routinely obtained. Large-area GaInP/GaAs heterojunction bipolar transistors (HBTs) show a high current gain of 225 for
base sheet resistance of 400 ohm/sq. The devices also exhibit excellent high-frequency characteristics. A cut-off frequency
of 48 GHz and a maximum oscillation frequency of 60 GHz have been obtained. These results demonstrate the high potential capability
of CBE for high-throughput GaInP/GaAs HBT production. 相似文献
16.
L. C. Su S. T. Pu G. B. Stringfellow J. Christen H. Selber D. Bimberg 《Journal of Electronic Materials》1994,23(2):125-133
GaxIn1-x P layers with x ≈ 0.5 have been grown by atmospheric pressure organometallic vapor phase epitaxy on GaAs substrates with
10 micron wide, [110]-oriented grooves produced photolithographically on the surface. The [110] steps and the misorientation
produced at the edges of the grooves have been found to have important effects on the formation of the Cu-Pt ordered structure
(ordering on {111} planes) in the GaInP layers during growth. In this work, the groove shape is demonstrated to be critically
important. For the optimum groove shape, with a maximum angle to the (001) surface of between 10 and 16°, single domains of
the (-111) and (1-11) variants of the Cu-Pt ordered structure are formed on the two sides of the groove. Shallow (≤0.25 μm
deep) grooves, with maximum angles of <10°, are less effective. Within the large domains on each side of the groove, small
domains of the other variant are observed. The boundary between the two domains is seen to wander laterally by a micron or
more during growth, due to the change in shape of the groove during growth. For deep (1.5 μm) grooves, with maximum angles
to the (001) plane of 35°, only a single variant is formed on each side of the groove. However, the domains are small, dispersed
in a disordered matrix. For substrates with deep grooves on a GaAs substrate misoriented by 9° toward the [-110] direction,
an interesting and useful pattern is produced. One half of the groove is a single domain which shrinks in size as the growth
proceeds. The other half of the groove, where the misorientation is larger, is disordered. Thus, every groove contains large
(>1 μm2 cross-sectional area and several mm long) regions of highly ordered and completely disordered material separated by no more
than a few microns. This allows a direct determination of the effect of ordering on the bandgap of the material using cathodoluminescence
(CL) spectroscopy. The 10K photoluminescence (PL) consists of three distinct peaks at 1.94, 1.88, and 1.84 eV. High resolution
CL images reveal that the peaks come from different regions of the sample. The high energy peak comes from the disordered
material and the low energy peak comes from the large ordered domains. Electron microprobe measurements of the solid composition
demonstrate that the shift in emission energy is not due to changes in solid composition. This is the firstdirect verification that ordering causes a reduction in bandgap of any III/V alloy. Decreasing the Ga0.5In0.5P growth rate from the normal 2.0 to 0.5 μ/h is found to enhance ordering in layers grown on planar GaAs substrates. Transmission
electron diffraction results show that the domain size also increases significantly. For material grown on exactly (001)-oriented
substrates, a pronounced [001] streaking of the superlattice spots is observed. This is correlated with the presence of a
dense pattern of fine lines lying in the (001) plane in the transmission electron micrographs. The PL of this highly ordered
material consists of a single peak that shifts to higher energy by > 110 meV as the excitation intensity is increased by several
orders of magnitude. 相似文献
17.
Pei‐Hsuan Lee Hsien‐Cheng Tseng Jung‐Hua Chou 《International Journal of Numerical Modelling》2010,23(1):32-41
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. 相似文献
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19.
808 nm大功率无铝有源区非对称波导结构激光器 总被引:2,自引:2,他引:2
采用分别限制非对称波导结构,将光场从对称分布变为非对称分布,降低了载流子光吸收损耗,并允许p型区具有更高的掺杂水平,从而使器件电阻降低.对GaAsP/GaInP张应变单量子阱(SQW)非对称波导结构激光器的光场特性进行了理论分析,设计了波导层厚度,并制作了波长为808 nm的无铝有源区大功率半导体激光器.器件综合特性测试结果为:腔长900μm器件的阈值电流密度典型值为400 A/cm2,内损耗低至1.0 cm-1;连续工作条件下,150μm条宽器件输出功率达到6 W,最大斜率效率为1.25 W/A.器件激射波长为807.5 nm,平行和垂直结的发散角分别为3.0°和34.8°.20~70℃范围内特征温度达到133 K.结果表明,分别限制非对称波导结构是降低内损耗,提高大功率半导体激光器特性的有效措施. 相似文献
20.
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Lsc,Voc和Pmax的衰降幅度均增大;但随质子辐照能量的增加,Lsc,Voc和Pmax的衰降幅度均减小.实验中0.28MeV质子辐照引起电池Lsc,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. 相似文献