We demonstrate a vertical AlGaN DUV LED with an emission wavelength of 272 nm and submicron thickness. The device epilayers thickness is reduced to ~670 nm by a combination of wafer bonding and thinning techniques, and this results in the thinnest vertical DUV LED reported to date. A light-emitting surface with root mean square value of 74.7 nm is also induced by thinning process without any other surface-roughing treatments. An n-contact electrode with a mesh geometry is adopted to expose the emission region, while the bottom metal electrode functions as a reflector to reflect downward-propagating light in an upward direction.

Tl-2212 superconducting films were fabricated on r-cut sapphire substrates buffered with (00l)-oriented CeO2 films. The buffer layers were deposited by the cerium dioxide sputtering target and the RF magnetron sputtering method. The epitaxial growth of CeO2 films on r-cut sapphire substrates was obtained over a wide range of sputtering parameters, such as temperature, pressure, power and Ar/O2 ratio. The Tl-2212 films grown on these buffer layers subsequently were purely c-axis orientation. The critical transition temperature of the best film was 105.6 K, the critical current density was 2.8 MA/cm2 (77 K, 0 T) and the surface resistance was 435 μΩ (10 GHz, 77 K).