Enhanced Conversion Efficiency in Back-Contact CMOS Photovoltaic Devices by Surface Engineering
| Autor: | Jia-fa Chen, 陳家發 |
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| Rok vydání: | 2015 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 103 Surface passivation and antireflection strongly affect the conversion efficiency of back-contact CMOS photovoltaic devices. Enhanced device performance is obtained by reducing the surface reflection and the minority carrier recombination. In order to achieve efficient back-contact CMOS photovoltaic device in standard bulk CMOS process, in this work we thin down the device substrate by mechanical grinding and lapping process in order to remove low-lifetime bulk substrate and increase the photocurrent collection efficiency. Thinned photovoltaic devices show an increase in conversion efficiency from originally 2~6% to 12~16% depending on the CMOS process. Supercritical carbon dioxide fluid process is then conducted for surface passivation of CMOS photovoltaic devices in order to reduce the surface recombination and thus increase the short-circuit current. Compared to other passivation techniques such as thermal oxidation or PECVD oxide deposition that requires high-temperature atmosphere, supercritical CO2 fluid is a low-temperature process that is much suitable to serve as the back-end process for CMOS photovoltaic devices. Afterward, a metal-assisted chemical etching process is then conducted to produce random silicon nanowire array to reduce the surface reflectivity from originally 30~40% down to only 2~4%. Enlarge surface area in silicon nanowire array also leads to a higher oxygen content after supercritical CO2 fluid treatment, as compared to planar surface. All efforts lead to an ultimate efficiency of 21.22% in silicon nanowire decorated back-contact CMOS photovoltaic devices. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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