Abstract
InGaN alloy systems are promising materials for device applications in optoelectronics. For an accurate design of III-nitride devices, a proper knowledge of their optical properties is important. However, the natural crystalline form of group-III nitrides, the wurtzite structure, induces strong macroscopic polarization fields at the interface, which affects the emission efficiencies. Conversely, using InGaN alloy systems coupled with colloidal nanocrystals to form hybrid materials can allow a significant breakthrough in optical emission and efficiency. This has become one of the most important research fields for improving the efficiency of InGaN light-emitting diodes (LEDs) in recent years. We conducted a systematic study of the optical properties of InGaN nanorods and InGaN-colloidal gold nanocrystals hybrid system. In chapter 1, we introduce the research background for group-III nitrides. In chapter 2, we describe related experimental techniques, such as plasmon-assisted molecular beam epitaxy, photoluminescence, and synthesis of colloidal gold nanocrystal technology. Chapter 3 presents a study on the growth and optical properties of InGaN nanorod arrays in a variety of emission bands. The research contained growing entire composition tenability of InGaN nanorod arrays and being minimized the carrier localization or/and the piezofield at the InGaN alloy systems. Chapter 4 shows a strong photoluminescence enhancement from the surface-plasmon-mediated hybrid system, which is formed with red-emitting InGaN and colloidal gold nanocrystals. This could be useful for improving emission efficiency in InGaN-based optoelectronic devices. Chapter 5 presents a three-dimensional nano-scale plasmonic green laser breaking through the optical diffraction limit by combining an InGaN nanorod bundle and colloidal gold nanocrystals. This is a step toward reducing the size of optical laser elements. Chapter 6 presents the scanning near-field optical microscopy (SNOM) measurement for observing the propagating behavior of a surface plasmon polarition inside colloidal gold nanocrystals. Finally, chapter 7 offers conclusions for this study and our perspectives on future research topics for the InGaN alloy system. It would be useful for future optoelectronic device applications.