研究概要 |
The direct-bandgap III-Nitride semiconductor family and its alloy span the widest spectral range among all the semiconductors, ranging from the infrared (InN @ 0.65 eV) through the visible and the ultra-violet (UV) (GaN @ 3.42 eV) to the deep UV range (AlN @ 6.2 eV). This unique property provides it to be the most promising candidate for the next-generation photovoltaic applications.However, the inferior crystalline quality in the active region, difficulty in achieving p-type in In-rich InxGa1-xN, and poor understanding of the transport across the heterojunctions hinder the development in high conversion efficiency solar cells. On the other hand, the Si-based solar cells with crystalline, polycrystalline, or amorphous have been well developed. We propose to deposit p-type polycrystalline Si or a-Si thin film on the high-quality n-type InGaN film to develop heterojunction solar cells. This novel device concept can avoid the puzzle of p-type doping in In-rich InGaN, and extend the optical absorption by adjusting the In composition in InGaN and/or doping in the p-type Si. P-type amorphous Si was deposited by using both sputtering and plasma enhanced chemical vapor deposition (PECVD) method. First, we successfully deposit amorphous Si on n-type InGaN by PECVD deposition. Then, the devices are wire bonded to a holder. The photovoltaic properties of the Si/InGaN solar cell are measured.The heterojunction indicated a very good rectifying characteristics, showing the p-n junction behavior.The photovoltaic properties are achieved.
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