Template-free synthesis of helical hexagonal microtubes of indium nitride

Single crystalline indium nitride (InN) helical microtubes with a hexagonal hollow cross section have been synthesized in bulk quantities by nitriding indium oxide powder in ammonia flux. As-prepared InN microtubes grow along the [0001] direction with typical outer diameters of 1-3 mu m, wall thickness of 50-80 nm and lengths up to hundreds of microns. The InN microtubes exhibit both right-handed and left-handed helicities with helical angles ranging from zero to about 30 degrees. Variation of helicity can be observed in a single tube. A number of observations demonstrate that the growth of the tubular structure occurs by the spiraling of the warped InN nanobelts. Photoluminescence spectrum of the microtubes presents a strong emission peak centered at 700 nm at room temperature. (c) 2005 American Institute of Physics.