scholarly journals Release of Impurities From Structural Defects in Polycrystalline Silicon Solar Cells

1997 ◽  
Vol 469 ◽  
Author(s):  
S. A. McHugo ◽  
M. Imaizumi
Keyword(s):  
Solar Cells ◽  
Polycrystalline Silicon ◽  
Minority Carrier ◽  
Structural Defects ◽  
Thermal Treatments ◽  
Silicon Matrix ◽  
X Ray ◽  
Metal Impurities ◽  
Carrier Recombination ◽  
Metallic Impurities

ABSTRACTIt is critical to understand the behavior of metallic impurities in polycrystalline silicon used for solar cells. These impurities significantly increase the minority carrier recombination rate and, in turn, degrade cell performance. Impurity gettering is a commonly used method to remove these impurities from the material, however, past work has suggested that impurity release from structural defects drastically limits the gettering process. Presently, there is only a limited understanding of impurity release from structural defects. In this work, a correlation between structural defects and the location of metal impurities in as-grown material is established and the release of nickel and copper from structural defects in polycrystalline silicon was studied in as-grown material and after sequential thermal treatments which dissolve the impurities into the silicon matrix. Synchrotron-based x-ray fluorescence impurity mapping with spatial resolution of ≈ 1μm, was used to determine impurity distributions after each thermal treatment.

scholarly journals Interface Study of ITO/ZnO and ITO/SnO2Complex Transparent Conductive Layers and Their Effect on CdTe Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Tingliang Liu ◽  
Xing Zhang ◽  
Jingquan Zhang ◽  
Wenwu Wang ◽  
Lianghuan Feng ◽  
...  
Keyword(s):  
Solar Cells ◽  
Photoelectron Spectroscopy ◽  
Minority Carrier ◽  
Rf Magnetron Sputtering ◽  
X Ray ◽  
Cdte Solar Cells ◽  
Carrier Recombination ◽  
Vis Spectroscopy ◽  
Interface Characteristic ◽  
Interface Study

Transparent ITO/ZnO and ITO/SnO2complex conductive layers were prepared by DC- and RF-magnetron sputtering. Their structure and optical and electronic performances were studied by XRD, UV/Vis Spectroscopy, and four-probe technology. The interface characteristic and band offset of the ITO/ZnO, ITO/SnO2, and ITO/CdS were investigated by Ultraviolet Photoelectron Spectroscopy (UPS) and X-ray Photoelectron Spectroscopy (XPS), and the energy band diagrams have also been determined. The results show that ITO/ZnO and ITO/SnO2films have good optical and electrical properties. The energy barrier those at the interface of ITO/ZnO and ITO/SnO2layers are almost 0.4 and 0.44 eV, which are lower than in ITO/CdS heterojunctions (0.9 eV), which is beneficial for the transfer and collection of electrons in CdTe solar cells and reduces the minority carrier recombination at the interface, compared to CdS/ITO. The effects of their use in CdTe solar cells were studied by AMPS-1D software simulation using experiment values obtained from ZnO, ITO, and SnO2. From the simulation, we confirmed the increase ofEff, FF,Voc, andIscby the introduction of ITO/ZnO and ITO/SnO2layers in CdTe solar cells.

scholarly journals Interactions Of Structural Defects With Metallic Impurities In Multicrystalline Silicon

1996 ◽  
Vol 442 ◽  
Author(s):  
S. A. McHugo ◽  
H. Hieslmair ◽  
E. R. Weber ◽  
M. D. Rosenblum ◽  
J. P. Kalejs
Keyword(s):  
Solar Cell ◽  
Multicrystalline Silicon ◽  
Structural Defects ◽  
Device Performance ◽  
X Ray ◽  
Cell Processing ◽  
Metal Impurities ◽  
Fluorescence Measurements ◽  
Incomplete Removal ◽  
Metallic Impurities

AbstractInteractions between structural defects and metallic impurities were studied in multicrystalline silicon for solar cell applications. The objective was to gain insight into the relationship between solar cell processing, metallic impurity behavior and the resultant effect on material/device performance. With an intense synchrotron x-ray source, high sensitivity x-ray fluorescence measurements were utilized to determine impurity distributions with a spatial resolution of ≈ lμm. Diffusion length mapping and final solar cell characteristics gauged material/device performance. The materials were tested in both the as-grown state and after full solar cell processing. Iron and nickel metal impurities were located at structural defects in asgrown material, while after solar cell processing, both impurities were still observed in low performance regions. These results indicate that multicrystalline silicon solar cell performance is directly related to metal impurities which are not completely removed during typical processing treatments. A discussion of possible mechanisms for this incomplete removal is presented.

scholarly journals Fabrication of Large-Grain Thick Polycrystalline Silicon Thin Films via Aluminum-Induced Crystallization for Application in Solar Cells

2013 ◽  
Vol 2013 ◽  
pp. 1-4
Author(s):  
Hsiao-Yeh Chu ◽  
Min-Hang Weng ◽  
Chen Lin
Keyword(s):  
Solar Cells ◽  
Polycrystalline Silicon ◽  
X Ray Diffraction ◽  
X Ray ◽  
Second Stage ◽  
Silicon Thin Films ◽  
Si Films ◽  
Two Stages ◽  
Induced Crystallization ◽  
Aluminum Induced Crystallization

The fabrication of large-grain 1.25 μm thick polycrystalline silicon (poly-Si) films via two-stage aluminum-induced crystallization (AIC) for application in thin-film solar cells is reported. The induced 250 nm thick poly-Si film in the first stage is used as the seed layer for the crystallization of a 1 μm thick amorphous silicon (a-Si) film in the second stage. The annealing temperatures in the two stages are both 500°C. The effect of annealing time (15, 30, 60, and 120 minutes) in the second stage on the crystallization of a-Si film is investigated using X-ray diffraction (XRD), scanning electron microscopy, and Raman spectroscopy. XRD and Raman results confirm that the induced poly-Si films are induced by the proposed process.

Modeling the Performance of Biaxially-Textured Silicon Solar Cells

2014 ◽  
Vol 1670 ◽  
Author(s):  
Joel B. Li ◽  
Bruce M. Clemens
Keyword(s):  
Grain Size ◽  
Solar Cells ◽  
Polycrystalline Silicon ◽  
Silicon Solar Cells ◽  
Device Performance ◽  
Performance Gain ◽  
Carrier Recombination ◽  
Out Of Plane ◽  
Performance Gains ◽  
Tcad Sentaurus

ABSTRACTGrain boundaries (GBs) in polycrystalline silicon (poly-Si) thin film solar cells are frequently found to be detrimental for device performance. Biaxiallytextured silicon with grains that are well-aligned in-plane and out-of-plane can possess fewer GB defects. In this work, we use TCAD Sentaurus device simulator and known experimental work to investigate and quantify the potential performance gains of biaxially-textured silicon. Simulation shows there can be performance gain from well-aligned grains when GB defects dominate carrier recombination or when grains are small. On the other hand, when intra-grain defects dominate recombination and grains are large, well-aligned grains do not lead to much performance gain. Another important result from our simulation is when intra-grain and GB defects are few, Jsc is almost independent of grain size while Voc drops with decreasing grain size.

Direct Correlation of Solar Cell Performance with Metal Impurity Distributions in Polycrystalline Silicon using Synchrotron-Based X-ray Analysis

1998 ◽  
Vol 524 ◽  
Author(s):  
S. A. McHugo ◽  
A. C. Thompson ◽  
G. Lamble ◽  
A. MacDowell ◽  
R. Celestre ◽  
...  
Keyword(s):  
Solar Cells ◽  
Solar Cell ◽  
Polycrystalline Silicon ◽  
Current Method ◽  
Chemical State ◽  
Limiting Factors ◽  
Metal Impurity ◽  
Solar Cell Performance ◽  
X Ray ◽  
X Ray Absorption

ABSTRACTThe work presented here directly measures metal impurity distributions and their chemical state in as-grown and fully processed polycrystalline silicon used for terrestrial-based solar cells. The goal was to determine if a correlation exists between poorly performing regions of solar cells and metal impurity distributions as well as to ascertain the chemical state of the impurities. Synchrotron-based x-ray fluorescence mapping and x-ray absorption spectroscopy, both with a spatial resolution of lμm, were used to measure impurity distributions and chemical state, respectively, in poorly performing regions of polycrystalline silicon. The Light Beam Induced Current method was used to measure minority carrier recombination in the material in order to identify poor performance regions. We have detected iron, chromium, nickel, gold and copper impurity precipitates and we have recognized a direct correlation between impurity distributions and poor performing regions in both as-grown and fully processed material. Furthermore, from x-ray absorption studies, we have initial results, indicating that the Fe in this material is in oxide form, not FeSi2,. These results provide a fundamental understanding into the efficiency-limiting factors of polycrystalline silicon solar cells as well as yielding insight for methods of solar cell improvement.

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