Metal Organic Chemical Vapor Deposition Growth of
| Autor: | Tran, Binh Tinh, 陳平淨 |
|---|---|
| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 The main objective of the dissertation is to develop wide bandgap InxGa1-xN and InxAl1-xN on Si substrates for photovoltaic applications (solar cell and ultraviolet photodiode) with high In content that can be integral component of photovoltaic devices to achieve high efficiency. The III-Nitride semiconductor materials, which consist of InN, AlN, GaN, and their alloys, have a high potential in the development of high efficiency photovoltaic due to its wide direct bandgap cover a spectral range from the infrared to the ultraviolet, electronic and optical properties. However, the growth of high-crystalline-quality InxGa1-xN films in the full composition range is also highly challenging because the large lattice mismatch between InN and GaN causes a solid-phase miscibility gap due to the low solubility between these two materials. This is one of the major challenges for the growth of InxGa1-xN and InxAl1-xN on any substrates. In this present work, by improving the buffer layer, controlling defects and phase separation using Metal Organic Chemical Vapor Deposition (MOCVD). The heterostructure InxGa1-xN/GaN with about 40% In content and lattice-matched InxAl1-xN to GaN were successfully grown on a Si (111) substrates and fabricated into solar cell and ultraviolet photodiode devices with very high conversion efficiency. The research includes three approaches. The electro-optic characteristics of a n-In0.4Ga0.6N/p-Si hetero-structure solar cell on Si substrate with Al and ITO (or Ti/Al/Ni/Au) materials for p and n-type contacts were grown, fabricated and investigated. The solar cell devices with ITO as n-type contacts were also compared to the solar cell using Ti/Al/Ni/Au as n-type contact in this study. The device with ITO contact exhibited an open-circuit voltage (Voc) of 1.52 V and a short-circuit current density (Jsc) of 8.68 mA/cm2 with 54% fill factor. The conversion and external quantum efficiency (EQE) of the solar cell were 7.12 and 20.8%, respectively. Besides, a relationship between VOC and In content in the InxGa1-xN alloys for this type of solar cell was also derived. High quality InxAl1-xN/GaN hetero-structures were also grown on Si substrates with various indium compositions (x = 10.2, 16.2 and 17.6%). The ultraviolet photodiode fabricated based on In0.176Al0.838N/GaN structure shows excellent device characteristics with a low leakage current of 0.12 μA, and a high spectral response. It has good quantum efficiency of 94 mA/W and 44% at 265 nm. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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