This project aims to understand the growth mechanism(s) of single crystal zinc oxide (ZnO) microtubes and their physical and characteristics relevant to device applications. Normally, ZnO single crystals have been fabricated in three forms: bulk crystals, thin films and nanowires/nanorods. Recently, the principal investigators have fabricated ZnO single crystal microtubes using a novel self-encapsulated microwave growth (SEMG) method. The ZnO single crystals are grown in hexagonal hollow microtube shapes with faceted ends and side surfaces. Through fabrication of high quality dimension-controlled ZnO single crystal microtubes, fundamental growth mechanisms and kinetics of ZnO single crystal tubes growth in SEMG conditions will be investigated. A variety of measurements will be conducted to characterize the physical/optical/electrical and coupled properties of the ZnO single crystals such as photosensitivity, photoluminescence, piezoelectricity, & defect/carrier densities. Potential for electric pumped longitudinal single mode laser and whispering gallery mode tunable filter applications will also be explored. Additionally, nitrogen-in-diffusion treatment of freestanding microtubes will be investigated to fabricate p-n junction for electric field pumped emissions. *** The project addresses fundamental materials research with strong technological relevance to electronics and photonics, and effectively integrates research and education. The exploration and further understanding of the novel single crystal ZnO hollow hexagonal microtube materials system may provide the potential for advanced optoelectronic devices. This project provides interdisciplinary research and educational opportunities for graduate and undergraduate students, and actively seeks to broaden research participation by members of underrepresented groups.
