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Final PhD Dissertation by Lila Raj.pdf (11.2 MB)

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Spectroscopic Ellipsometry Studies of Thin Film a-Si:H Solar Cell Fabrication by Multichamber Deposition in the n-i-p Substrate Configuration

Dahal, Lila R
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1365202814

Abstract Details

2013, Doctor of Philosophy, University of Toledo, College of Arts and Sciences.
Real time spectroscopic ellipsometry (RTSE), and ex-situ mapping spectroscopic ellipsometry (SE) are powerful characterization techniques capable of performance optimization and scale-up evaluation of thin film solar cells used in various photovoltaics technologies. These non-invasive optical probes employ multichannel spectral detection for high speed and provide high precision parameters that describe (i) thin film structure, such as layer thicknesses, and (ii) thin film optical properties, such as oscillator variables in analytical expressions for the complex dielectric function. These parameters are critical for evaluating the electronic performance of materials in thin film solar cells and also can be used as inputs for simulating their multilayer optical performance. In this Thesis, the component layers of thin film hydrogenated silicon (Si:H) solar cells in the n-i-p or substrate configuration on rigid and flexible substrate materials have been studied by RTSE and ex-situ mapping SE. Depositions were performed by magnetron sputtering for the metal and transparent conducting oxide contacts and by plasma enhanced chemical vapor deposition (PECVD) for the semiconductor doped contacts and intrinsic absorber layers. The motivations are first to optimize the thin film Si:H solar cell in n-i-p substrate configuration for single-junction small-area dot cells and ultimately to scale-up the optimized process to larger areas with minimum loss in device performance. Deposition phase diagrams for both i- and p-layers on 2" x 2" rigid borosilicate glass substrate were developed as functions of the hydrogen-to-silane flow ratio in PECVD. These phase diagrams were correlated with the performance parameters of the corresponding solar cells, fabricated in the Cr/Ag/ZnO/n/i/p/ITO structure. In both cases, optimization was achieved when the layers were deposited in the protocrystalline phase. Identical solar cell structures were fabricated on 6" x 6" borosilicate glass with 256 cells followed by ex-situ mapping SE on each cell to achieve better statistics for solar cell optimization by correlating local structural parameters with solar cell parameters. Solar cells of similar structure were also fabricated on flexible polymer substrates in the roll-to-roll configuration. In this configuration as well, RTSE was demonstrated as an effective process monitoring and control tool for thin film photovoltaics.
Robert Collins , Dr. (Committee Chair)
Nikolas Podraza, Dr. (Committee Member)
Song Cheng, Dr. (Committee Member)
Sanjay Khare, Dr. (Committee Member)
Andre Ferlauto, Dr. (Committee Member)
312 p.
Physics
real time spectroscopic ellipsometry; photovoltaics; a-Si:H solar cell; deposition phase diagram; spatial phase diagram; roll-to-roll deposition; back-reflector; phasmon resonance; surface roughness evolution; effective medium theory

Recommended Citations

Citations

  • Dahal, L. R. (2013). Spectroscopic Ellipsometry Studies of Thin Film a-Si:H Solar Cell Fabrication by Multichamber Deposition in the n-i-p Substrate Configuration [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1365202814

    APA Style (7th edition)

  • Dahal, Lila . Spectroscopic Ellipsometry Studies of Thin Film a-Si:H Solar Cell Fabrication by Multichamber Deposition in the n-i-p Substrate Configuration. 2013. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1365202814.

    MLA Style (8th edition)

  • Dahal, Lila . "Spectroscopic Ellipsometry Studies of Thin Film a-Si:H Solar Cell Fabrication by Multichamber Deposition in the n-i-p Substrate Configuration." Doctoral dissertation, University of Toledo, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1365202814

    Chicago Manual of Style (17th edition)

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© 2013, all rights reserved.
This open access ETD is published by University of Toledo and OhioLINK.