A deep-ultraviolet (DUV) emitter has been created from a film of boron nitride nanotubes (BNNTs) by scientists at Deakin University (Waurn Ponds, Australia), the Australian National University (Canberra, Australia), and the National Synchrotron Radiation Research Center (Hsinchu, Taiwan). The material, which emits in a band around 225 nm (5.51 eV), could find use as a nanosized DUV light source for upcoming micro- and nanophotonic applications.
A boron-ink-coating method was used to fabricate high-purity BNNT films with very uniform properties on silicon dioxide coated silicon wafers; the material was then annealed in vacuum. The resulting BNNTs had diameters of 2-10 nm and tube walls with two to ten molecular layers. Higher-energy excitation photons from a vacuum-ultraviolet beamline created photoluminescence in the BNNTs for the experiment. The emission full-width at half-maximum (FWHM) was 30.6 nm at a temperature of 10K, and 31.8 nm at 293K. Good crystallinity is essential to achieve emission in a single strong band; BNNTs with larger diameters (40-80 nm) and more layers had weak DUV emission. In addition, omitting the vacuum-annealing step degraded the spectrum-a characteristic that the BNNTs share with carbon nanotubes. Contact Lu Hua Li at [email protected].