Abstract: Based on the unique core-shell GaN nanorod (NR) growth technique built by this research team and their related research accomplishments in the past few years, several key issues will be further studied experimentally and theoretically in this project. They include (1) implementation of phosphor-free white-light generation in a multi-section NR light-emitting diode (LED) array with circular or elliptical cross-sectional circumscription in individual NRs, (2) theoretical investigations of GaN NR growth mechanisms based on the pulsed growth technique with metalorganic chemical vapor deposition and related experimental verifications, and (3) fabrication of nano-cavity LEDs with whispering-gallery resonance (WGR) and photonic bandgap behaviors. To broaden the overall emission spectrum of an NR array for implementing white-light generation, current spreading on NR sidewalls will be improved and indium incorporation in growing sidewall InGaN/GaN quantum wells (QWs) will be enhanced based on proposed novel growth techniques. The theoretical studies on NR growth mechanisms include the dependencies of NR cross-sectional size and height on growth condition, the dependence of the tapering morphology evolution of an NR on the pulsed growth parameters, the transition process from one uniform section into another, and the variations of well width and indium content in the QWs at different sidewall heights or in different uniform sections. For fabricating nano-cavity NR LED devices, the WGR behaviors in a single NR will be investigated first, followed by the study on the coupled WGR characteristics in an NR array. An NR array to form a photonic bandgap will be designed and fabricated for combining with the WGR behaviors and the surface plasmon coupling effects, which are induced by forming Ag nanoparticles on NR sidewalls, to study the overall resonance properties in such a nano-cavity LED structure.
The accomplishments of this project can help in promoting the technology of solid state lighting, which is a key issue for saving energy and reducing carbon dioxide on the earth. Currently, Taiwan is under a lot of international pressures for contributing to carbon dioxide reduction. This project can help in this social issue. Also, LED is an important high-tech industry in Taiwan. This project aims at the development of novel LED techniques and hence can help in this economical issue. Meanwhile, physical and technical subjects are to be explored in this project for promoting the academic development.
multi-section nanorod light-emitting diode
pulsed growth mechanism