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Zhiquan Huang Dissertation final2.pdf (39.76 MB)

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Spectroscopic Ellipsometry Studies of Thin Film a-Si:H/nc-Si:H Micromorph Solar Cell Fabrication in the p-i-n Superstrate Configuration

Huang, Zhiquan
http://rave.ohiolink.edu/etdc/view?acc_num=toledo1460919549

Abstract Details

2016, Doctor of Philosophy, University of Toledo, Physics.
Spectroscopic ellipsometry (SE) is a non-invasive optical probe that is capable of accurately and precisely measuring the structure of thin films, such as their thicknesses and void volume fractions, and in addition their optical properties, typically defined by the index of refraction and extinction coefficient spectra. Because multichannel detection systems integrated into SE instrumentation have been available for some time now, the data acquisition time possible for complete SE spectra has been reduced significantly. As a result, real time spectroscopic ellipsometry (RTSE) has become feasible for monitoring thin film nucleation and growth during the deposition of thin films as well as during their removal in processes of thin film etching. Also because of the reduced acquisition time, mapping SE is possible by mounting an SE instrument with a multichannel detector onto a mechanical translation stage. Such an SE system is capable of mapping the thin film structure and its optical properties over the substrate area, and thereby evaluating the spatial uniformity of the component layers. In thin film photovoltaics, such structural and optical property measurements mapped over the substrate area can be applied to guide device optimization by correlating small area device performance with the associated local properties. In this thesis, a detailed ex-situ SE study of hydrogenated amorphous silicon (a Si:H) thin films and solar cells prepared by plasma enhanced chemical vapor deposition (PECVD) has been presented. An SE analysis procedure with step-by-step error minimization has been applied to obtain accurate measures of the structural and optical properties of the component layers of the solar cells. Growth evolution diagrams were developed as functions of the deposition parameters in PECVD for both p-type and n-type layers to characterize the regimes of accumulated thickness over which a-Si:H, hydrogenated nanocrystalline silicon (nc-Si:H) and mixed phase (a+nc)-Si:H thin films are obtained. The underlying materials for these depositions were newly-deposited intrinsic a-Si:H layers on thermal oxide coated crystalline silicon wafers, designed to simulate specific device configurations. As a result, these growth evolution diagrams can be applied to both p-i-n and n-i-p solar cell optimization. In this thesis, the n-layer growth evolution diagram expressed in terms of hydrogen dilution ratio was applied in correlations with the performance of p-i-n single junction devices in order to optimize these devices. Moreover, ex-situ mapping SE was also employed over the area of multilayer structures in order to achieve better statistics for solar cell optimization by correlating structural parameters locally with small area solar cell performance parameters. In the study of (a-Si:H p-i-n)/(nc-Si:H p-i-n) tandem solar cells, RTSE was successfully applied to monitor the fabrication of the top cell, and efforts to optimize the nanocrystalline p-layer and i-layer of the bottom cell were initiated.
Robert Collins (Advisor)
467 p.
Materials Science; Physics
Spectroscopic ellipsometry, real time spectroscopic ellipsometry ,optical properties, thin film nucleation and growth, photovoltaics, amorphous silicon, nanocrystalline silicon, Growth evolution diagrams, tandem solar cell

Recommended Citations

Citations

  • Huang, Z. (2016). Spectroscopic Ellipsometry Studies of Thin Film a-Si:H/nc-Si:H Micromorph Solar Cell Fabrication in the p-i-n Superstrate Configuration [Doctoral dissertation, University of Toledo]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1460919549

    APA Style (7th edition)

  • Huang, Zhiquan. Spectroscopic Ellipsometry Studies of Thin Film a-Si:H/nc-Si:H Micromorph Solar Cell Fabrication in the p-i-n Superstrate Configuration . 2016. University of Toledo, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=toledo1460919549.

    MLA Style (8th edition)

  • Huang, Zhiquan. "Spectroscopic Ellipsometry Studies of Thin Film a-Si:H/nc-Si:H Micromorph Solar Cell Fabrication in the p-i-n Superstrate Configuration ." Doctoral dissertation, University of Toledo, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=toledo1460919549

    Chicago Manual of Style (17th edition)

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© 2016, all rights reserved.
This open access ETD is published by University of Toledo and OhioLINK.