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Fabrication of Si/InGaN Heterojunction Solar Cells by RF Sputtering Method: Improved Electrical and Optical Properties of Indium Gallium Nitride (InGaN) Thin Films

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2017, Doctor of Philosophy (PhD), Ohio University, Physics and Astronomy (Arts and Sciences).
This dissertation presents a study on the fabrication of Indium Gallium Nitride (InGaN) based heterojunction solar cells using RF magnetron sputtering method. The goal of the study includes improving the electrical, optical and structural properties of InGaN thin films and examining their potential for photovoltaic applications and to reduce the parasitic resistive loses in solar cells. Reactive radio-frequency (RF) magnetron and Direct Current (DC) sputtering are deposition methods for thin films. The characterization techniques include Hall Effect measurement system for electrical properties, UV-Visible Spectroscopy for optical properties, X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Spectroscopy (EDXS) for structural properties and AM 1.5 G irradiance spectrum to measure current-voltage (IV curves) and photovoltaic measurements. Copper Oxide thin films and Beryllium Zinc Oxide thin films are fabricated and their properties are examined for their potential to pair with n-InGaN to form a p-n junction. We conclude Silicon (111) wafer has better electrical properties than RF deposited Copper oxide and BeZnO and used as p-type layer. Aluminum (Al) and Indium Tin Oxide (ITO) are used as back and front metallic contacts respectively. In this study, we present a simple method for optical bandgap tuning of Indium Gallium Nitride (InGaN) thin films by controlling the growth conditions in magnetron RF sputtering. Thin films with different Indium (In) atomic compositions, x = 0.02 to 0.57 are deposited on high temperature aluminosilicate glass and Silicon (111) substrates. Substrate temperature is varied from 35 oC to 450 oC. Total pressure of sputtering gas mixture is kept constant at 12 mTorr but partial pressures of Ar and N2 are varied. Ar partial pressure to total pressure ratio is varied from 0 to 0.75. Optical bandgap values from 1.4 eV to 3.15 eV, absorption coefficient values of ~ 104 /cm to ~ 7 x 105 /cm and critical film thickness values of 0.04 µm to 4 µm are measured. Resistivity values of 2.6x10-5 to 1.68x10-2 Ω.cm, mobility values of 0.119 to 1017 cm2/V. s, conductivity values of 0.595 x 103 to 37.3 x 103 mho/cm and bulk carrier concentration values -1020 to -1022 /m3 are recorded. To reduce parasitic loses, Aluminum Nitride (AlN) is used as buffer layer and solvent clean method is used to remove oxide layers. A short circuit current of 80 µA, Voc of 0.24 V, Fill Factor of 0.418 and efficiency of 0.015 % is measured for the solar cells.
Martin Kordesch (Advisor)
148 p.

Recommended Citations

Citations

  • Jakkala, P. K. (2017). Fabrication of Si/InGaN Heterojunction Solar Cells by RF Sputtering Method: Improved Electrical and Optical Properties of Indium Gallium Nitride (InGaN) Thin Films [Doctoral dissertation, Ohio University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1490714042486824

    APA Style (7th edition)

  • Jakkala, Pratheesh Kumar. Fabrication of Si/InGaN Heterojunction Solar Cells by RF Sputtering Method: Improved Electrical and Optical Properties of Indium Gallium Nitride (InGaN) Thin Films . 2017. Ohio University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1490714042486824.

    MLA Style (8th edition)

  • Jakkala, Pratheesh Kumar. "Fabrication of Si/InGaN Heterojunction Solar Cells by RF Sputtering Method: Improved Electrical and Optical Properties of Indium Gallium Nitride (InGaN) Thin Films ." Doctoral dissertation, Ohio University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=ohiou1490714042486824

    Chicago Manual of Style (17th edition)