Strain Release of InGaN/GaN Quantum Wells through Nano-hole Fabrication and Formation of Metal Particles for Surface Plasmon Study with the Anodic Aluminum Oxide Technique
| Autor: | Li-Guo Li, 李立國 |
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| Rok vydání: | 2008 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 96 In this research, we fabricate anodic alumina oxide (AAO) on GaN and InGaN/GaN quantum well (QW) structure. With the AAO technique, we can fabricate a thin aluminum oxide film with nano-pore array on the nitride structure, which is used as a mask to deposit metal nano-particle arrays on to study the surface plasmon (SP) characteristics, or to release the strain in the QW. Our first study is about the SP characteristics of a silver or gold nano-particle array on GaN template. We change the AAO process condition to control the hole diameter and interpore distance such that we can vary the particle size and density of the metal nano-particle array. We observe the SP absorption spectra and its resonance frequencies of different particle sizes and densities. The second study is about the strain relaxation phenomenon by fabricating nano-hole array patterns with the AAO technique on an InGaN/GaN QW structure. The effective strain relaxation, leading to the significant enhancement of emission efficiency and reduction of quantum-confined Stark effect (QCSE), in a high-indium InGaN/GaN QW structure via nano-pore fabrication on the sample surface with the anodic aluminum oxide technique is demonstrated. By generating nano-pores of 60 nm in size, 4.71 x 109 cm-2 in pore density, and a depth several nm above the QW, the internal quantum efficiency (IQE) can be increased by about three times and the QCSE is reduced by 2.5 times while the emission spectrum is blue-shifted by 14 nm in the green range. With this approach, it is possible to achieve a higher IQE and a smaller QCSE by relaxing the built-in strain of a higher-indium QW structure and blue-shifting its emission, when compared with a lower-indium sample of the same emission spectrum as the blue-shifted one. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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