Tunnel Junctions for III-V Multijunction Solar Cells Review

Tunnel Junctions, as addressed in this review, are conductive, optically transparent semiconductor layers used to join different semiconductor materials in order to increase overall device efficiency. The first monolithic multi-junction solar cell was grown in 1980 at NCSU and utilized an AlGaAs/AlGaAs tunnel junction. In the last 4 decades both the development and analysis of tunnel junction structures and their application to multi-junction solar cells has resulted in significant performance gains. In this review we will first make note of significant studies of III-V tunnel junction materials and performance, then discuss their incorporation into cells and modeling of their characteristics. A Recent study implicating thermally activated compensation of highly doped semiconductors by native defects rather than dopant diffusion in tunnel junction thermal degradation will be discussed. AlGaAs/InGaP tunnel junctions, showing both high current capability and high transparency (high bandgap), are the current standard for space applications. Of significant note is a variant of this structure containing a quantum well interface showing the best performance to date. This has been studied by several groups and will be discussed at length in order to show a path to future improvements.

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Non-Local Recombination in “Tunnel Junctions” of Multijunction Amorphous Si Alloy Solar Cells

MRS Proceedings ◽

10.1557/proc-336-717 ◽

1994 ◽

Vol 336 ◽

Cited By ~ 9

Author(s):

Jingya Hou ◽

Jianping Xi ◽

Frank Kampas ◽

Sanghoon Bae ◽

S. J. Fonash

Keyword(s):

Solar Cells ◽

Tunnel Junction ◽

Tunnel Junctions ◽

Energy Conversion Efficiency ◽

State Density ◽

Defect State ◽

Large Defect ◽

Recombination Mechanism ◽

Non Local ◽

Amorphous Si

ABSTRACTThis paper analyzes the charge transport in “tunnel junctions” of amorphous Si Material based multijunction solar cells and proposes some guidelines for making good “tunnel junctions” based on the analysis. The Mechanism of the current flow in these “tunnel” junctions is recombination. However, the recombination mechanism is not the usual localized recombination but is non-localized recombination. The energy analysis shows that the usual localized recombination will cause a large energy loss and result in much lower energy conversion efficiency and Voc than the experimentally measured values. In non-local recombination, opposite charge carriers located at different locations can recombine by tunneling into a defect state. Based on this Mechanism, a good “tunnel junction” should be thin, with a large defect state density in the middle region of the “tunnel junction”. Broad tail states material and a thin layer small band gap material in tunnel junctions may improve the non-local recombination by providing more intermediate states for charge to tunnel through.

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Awareness and Intertrial Activity in Verbal Conditioning

Psychological Reports ◽

10.2466/pr0.1969.25.2.455 ◽

1969 ◽

Vol 25 (2) ◽

pp. 455-460 ◽

Cited By ~ 2

Author(s):

Steven L. Mandel ◽

Leonard D. Goodstein

Keyword(s):

Naming Task ◽

Color Naming ◽

Performance Gain ◽

Experimental Conditions ◽

Sentence Construction ◽

Significant Performance ◽

Group A ◽

And Performance ◽

Performance Gains ◽

The Relationship

It was hypothesized that, in VOC, the relationship between awareness and performance gains would be a function of the experimental conditions during training. Fifty-six naive Ss were assigned to 1 of 4 experimental conditions. Each group performed the Taffel sentence-construction task. This was the only treatment given one group; a second group was required to perform a color-naming task between trials. A third group was required to write their “thoughts about the experiment” between blocks of trials, while a fourth group was required to perform both the intertrial and the inter-block tasks. All groups demonstrated significant performance gains. The color-naming task resulted in significantly less performance gain, as expected, but, contrary to expectation, did not significantly inhibit the development of awareness. The discrepancies between the present results and those of previous studies were explored as were the implications for understanding the VOC process.

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Optimum morphology and performance gains of organic solar cells

2011 37th IEEE Photovoltaic Specialists Conference ◽

10.1109/pvsc.2011.6186696 ◽

2011 ◽

Cited By ~ 3

Author(s):

Biswajit Ray ◽

Muhammad A. Alam

Keyword(s):

Solar Cells ◽

Organic Solar Cells ◽

And Performance ◽

Performance Gains

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Microcrystalline Silicon Tunnel Junctions for Amorphous Silicon-Based Multijunction Solar Cells

MRS Proceedings ◽

10.1557/proc-557-579 ◽

1999 ◽

Vol 557 ◽

Cited By ~ 3

Author(s):

A. S. Ferlauto ◽

Joohyun Koh ◽

P. I. Rovira ◽

C. R. Wronski ◽

R. W. Collins

Keyword(s):

Solar Cells ◽

Amorphous Silicon ◽

Tunnel Junction ◽

Single Phase ◽

Film Growth ◽

Tunnel Junctions ◽

Microcrystalline Silicon ◽

Evolutionary Phase ◽

Two Phases ◽

P Type

AbstractThe formation of tunnel junctions for applications in amorphous silicon (a-Si:H) based multijunction n-i-p solar cells has been studied using real time optics. The junction structure investigated in detail here consists of a thin (~200 Å) layer of n-type microcrystalline silicon (μc-Si:H) on top of an equally thin layer of p-type μc-Si:H, the latter deposited on thick (~2000 Å) intrinsic a-Si:H. Such a structure has been optimized in an attempt to obtain single-phase μc-Si:H with a high crystallite packing density and large grain size for both layers of the tunnel junction. We have explored the conditions under which grain growth is continuous across the p/n junction and conditions under which renucleation of n-layer grains can be ensured at the junction. One important finding of this study is that the optimum conditions for single-phase, high-density μc-Si:H n-layers are different depending on whether the substrate is a μc-Si:H p-layer or is a H2-plasma treated or untreated a-Si:H i-layer. Thus, the top-most μc-Si:H layer of the tunnel junction must be optimized in the multijunction device configuration, rather than in single cell configurations on a-Si:H i-layers. Our observations are explained using an evolutionary phase diagram for a-Si:H and μc-Si:H film growth versus thickness and H2-dilution ratio, in which the boundary between the two phases is strongly substrate-dependent.

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Application Performance on the Tri-Lab Linux Capacity Cluster - TLCC

International Journal of Distributed Systems and Technologies ◽

10.4018/jdst.2010040102 ◽

2010 ◽

Vol 1 (2) ◽

pp. 23-39 ◽

Cited By ~ 2

Author(s):

Mahesh Rajan ◽

Douglas Doerfler ◽

Courtenay T. Vaughan ◽

Marcus Epperson ◽

Jeff Ogden

Keyword(s):

Performance Analysis ◽

Large Capacity ◽

Application Performance ◽

Significant Performance ◽

Mpi Applications ◽

And Performance ◽

Performance Analysis Tools ◽

Performance Gains ◽

Detrimental Impact ◽

Memory Affinity

In a recent acquisition by DOE/NNSA several large capacity computing clusters called TLCC have been installed at the DOE labs: SNL, LANL and LLNL. TLCC architecture with ccNUMA, multi-socket, multi-core nodes, and InfiniBand interconnect, is representative of the trend in HPC architectures. This paper examines application performance on TLCC contrasting them with Red Storm/Cray XT4. TLCC and Red Storm share similar AMD processors and memory DIMMs. Red Storm however has single socket nodes and custom interconnect. Micro-benchmarks and performance analysis tools help understand the causes for the observed performance differences. Control of processor and memory affinity on TLCC with the numactl utility is shown to result in significant performance gains and is essential to attenuate the detrimental impact of OS interference and cache-coherency overhead. While previous studies have investigated impact of affinity control mostly in the context of small SMP systems, the focus of this paper is on highly parallel MPI applications.

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Preliminary Analysis of Solar Cell Interconnections Welding Parameters Using Design of Experiments for Future Optimization

Journal of Aerospace Technology and Management ◽

10.5028/jatm.cab.1151 ◽

2020 ◽

pp. 12-24

Author(s):

Graziela Fernanda de Souza Maia ◽

Marcelo Lopes de Oliveira e Souza ◽

Alírio Cavalcanti de Brito

Keyword(s):

Solar Cells ◽

Design Of Experiments ◽

Preliminary Analysis ◽

Welding Process ◽

Welding Parameters ◽

Solar Panels ◽

Space Applications ◽

Analysis And Design ◽

And Performance ◽

Big Cell

One of the processes that determine the reliability of solar panels used in space applications is the welding of interconnections between two adjacent solar cells. This process has various technologies, sequences and activities that have various characteristics, factors and parameters. Their combinations and values allow countless possibilities, making their adjustments time consuming, costly and exhausting. One way of abbreviating this, achieving competitiveness and meeting the needs of stakeholders is through the Analysis and Design of Experiments. This technique helps in optimizing the best adjustments to obtain the expected results. Thus, this paper presents a preliminary analysis of the parameters and their interactions of the welding process (by parallel-gap resistance welding) of interconnections between solar cells using design of experiments. In this welding process, the cell undergoes a certain level of degradation. For this reason, it is important to determine which process parameters are important and their proper levels, without big cell degradation. The result of this analysis can be used in the future to optimize the welding process meeting the design requirements for reliability and performance.

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