Direct synthesis of gallium oxide tubes, nanowires, and nanopaintbrushes.

We demonstrate bulk synthesis of highly crystalline beta-gallium oxide tubes, nanowires, and nanopaintbrushes using molten gallium and microwave plasma containing a mixture of monatomic oxygen and hydrogen. Gallium oxide nanowires were 20-100 nm thick and tens to hundreds of micrometers long. Transmission electron microscopy (TEM) revealed the nanowires to be highly crystalline and devoid of any structural defects. Results showed that multiple nucleation and growth of gallium oxide nanostructures could easily occur directly out of molten gallium exposed to an appropriate composition of hydrogen and oxygen in the gas phase. These gallium oxide nanostructures should be of particular interest for optoelectronic devices and catalytic applications.