Liquid Phase Epitaxially Grown Homojunctions in Gallium Aluminum Arsenide for Solar Cell Applications PDF Download

Author: Ward James Collis
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ISBN:
Category : Solar collectors
Languages : en
Pages : 306

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Author:
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Category : Aeronautics
Languages : en
Pages : 568

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Author:
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Category : Solar energy
Languages : en
Pages : 636

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Author: John C. Zolper
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ISBN:
Category : Solar cells
Languages : en
Pages : 156

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Author: Susan R. Huang
Publisher:
ISBN: 9781124479668
Category : Gallium
Languages : en
Pages :

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Multijunction structures composed of III-V materials grown on a III-V or Ge substrate are often employed to achieve high solar cell conversion efficiencies. However, it is advantageous to consider alternate substrates that can lower cost, such as the well developed Si, as a platform on which multi-junction solar structures can be grown. Growth of III-Vs on an alternate substrate such as Si requires careful consideration of the lattice constant mismatch as this will greatly influence the physical and electronic quality of the film. A material that is closely lattice matched with Si is Gallium phosphide (GaP). This lattice matching allows for good quality epitaxial growth and GaP can be alloyed with other III-V materials to tune the bandgap, which is an important property for multi-junction solar cells. In this work, liquid phase epitaxy (LPE) was used to grow GaP films on miscut and aligned Si (111) substrates. The films have been characterized by SEM and XRD to show that the GaP films are planar with uniform morphology and good crystal quality. The composition has been found by XPS and Auger spectroscopy to be GaP with 10-20% Si content. High resolution XRD analysis confirmed that the films are epitaxial and have a threading dislocation density of 2 x 10 6 cm -2 for growth on aligned Si (111) which is promising for the development of III-V/Si multi-junction solar cells. A four junction solar cell stack that includes a Si junction has a theoretical efficiency greater than 50%. In this structure, a GaP layer can act as a buffer layer on Si to growth other III-V materials with optimized bandgaps. Therefore, the effect of a GaP film on a Si solar cell was investigated. The results of this investigation show that growing a GaP layer on a Si solar cell fabricated by a diffusion process increases the series resistance and has lower Voc. Quantum efficiency measurements show that there is some reduction in efficiency of collection of carriers excited by wavelengths shorter than 450 nm which could be due to absorption in the GaP layer and recombination at the interface. A GaP layer grown on a p-type Si substrate exhibited similar current voltage characteristics as the GaP layer grown on a Si solar cell. SIMS depth profiling showed that phosphorus diffusion occurs during growth of GaP, creating a n-type doped. This indicates that a GaP layer can be grown on a Si substrate to directly make a solar cell. Epitaxial GaP layers have been grown on Si (111) substrates with high crystal quality which is promising for use as a buffer layer. Growth of GaP on Si can be used to directly fabricate a Si solar cell. This GaP/Si structure will be beneficial to solar cell and many other optoelectronic applications.

Author:
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ISBN:
Category : Metallurgy
Languages : en
Pages : 776

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Author: Standen Nigel Douglas
Publisher:
ISBN:
Category : Gallium arsenide
Languages : en
Pages : 162

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Author: Stephen Charles Smith
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Category :
Languages : en
Pages : 90

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Author: Margaret Folkard
Publisher:
ISBN: 9780642898746
Category : Gallium arsenide
Languages : en
Pages : 25

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Author: James D. Oliver
Publisher:
ISBN:
Category : Indium phosphide
Languages : en
Pages : 372

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