In-rich InGaN thin film growth by metal organic chemical vapor deposition
| Autor: | Sheng-han Yang, 楊勝涵 |
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| Rok vydání: | 2011 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 99 In this study, we have grown gallium nitride (GaN), indium gallium nitride (InGaN), and aluminum indium gallium nitride (AlInGaN) thin films on the n-GaN/Sapphire substrates by employing a home-made metal organic chemical vapor deposition (MOCVD) system. The material properties of these samples were characterized by using field emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS) and Photoluminescence (PL). At the beginning, we explored the effect of the growth pressure for the GaN thin films. We improved thin film’s quality and increased the growth rate by reducing the growth pressure down to 25 torr. In InXGa1-XN thin film growth, we found the indium content in InXGa1-XN could be increased by decreasing the growth pressure or the growth temperature, or by increasing TMIn/(TMIn+TMGa) input flow ratio or growth time. As a result, In-rich InXGa1-XN thin films that have x ratios in between 0.17 and 0.45 and exhibited single X-ray diffraction peak were grown. Comparing the elemental analysis of XPS with the XRD results, the two are consistent. For AlInGaN thin film growth, we fixed the TMIn/(TMIn+TMGa) input flow ratio and increased TMAl input flow. The lattice constant became smaller when the TMAl input flow was increased. Finally, we used AlInGAN as buffer layer to reduce lattice mismatch between In-rich InGaN and GaN. With 30 nm-thick AlInGaN buffer layer, the X-ray diffraction peak of the thin film shifted to left that indicated higher indium content. It was likely due to stress relaxation; In-rich InGaN was easier to grow. Moreover, using AlInGaN as a cladding material to grow multi-pair In0.43Ga0.57N/AlInGaN thin film structure, we found the X-ray diffraction profile was composed of two peaks with peak positions somewhat different from the original positions of In0.43Ga0.57N and AlInGaN. It was possibly resulted from lattice strain interaction and Al/Ga/In composition interdiffusion between layers during growth. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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