Ultraviolet light

About: Ultraviolet light is a research topic. Over the lifetime, 49494 publications have been published within this topic receiving 843151 citations.

A 342-nm ultraviolet AlGaN multiple-quantum-well laser diode

Abstract: The realization of semiconductor laser diodes and light-emitting diodes that emit short-wavelength ultraviolet light is of considerable interest for a number of applications including chemical/biochemical analysis, high-density data storage and material processing. Group III nitride materials are one of the most promising candidates for fabricating such devices. Here we describe an AlGaN multiple-quantum-well laser diode that emits light at 342 nm, the shortest wavelength ever reported for an electrically driven laser diode. To fabricate the laser, a low-dislocation-density AlGaN layer with an AlN mole fraction of 0.3 was grown on a sapphire substrate using a hetero facet-controlled epitaxial lateral overgrowth (hetero-FACELO) method1,2,3. An AlGaN multiple-quantum-well structure was then grown on the high-quality AlGaN layer. Lasing at a wavelength of 342.3 nm was observed under pulsed current mode at room temperature. Short-wavelength UV laser diodes are required for applications ranging from sensing, data storage and materials processing. Here, an electrically driven semiconductor laser that operates at 342.3 nm, the shortest wavelength so far, is reported. The device emits milliwatt-scale powers at room temperature when driven by pulsed current.

Toward the enhanced photoactivity and photostability of ZnO nanospheres via intimate surface coating with reduced graphene oxide

Abstract: A series of uniform ZnO nanospheres–reduced graphene oxide nanocomposites (ZnO–RGO NCs) with different weight addition ratios of RGO are successfully synthesized via a facile yet efficient method by intimately coating ZnO nanospheres (NSs) with RGO, which is afforded by electrostatic attraction between positively charged ZnO NSs and negatively charged graphene oxide (GO) in an aqueous medium at room temperature. The photocatalytic test of degradation of Rhodamine B shows that the optimal ZnO–10% RGO NCs exhibit a 5-fold enhancement of photoactivity than bare ZnO NSs, which is ascribed to the integrative synergetic effect of enhanced adsorption capacity, the decreased recombination of the electron–hole pairs and the enhanced ultraviolet light absorption intensity. Significantly, the recycled photoactivity tests show that, for ZnO–RGO NCs, the anti-photocorrosion of ZnO NSs is improved remarkably which is attributed to the effective hybridization of ZnO NSs with the RGO sheet via intimate surface coating. Such a significant photoactivity enhancement and anti-photocorrosion phenomenon can not be obtained by simply integrating RGO with ZnO NSs that are not subject to surface charge modification, which thus indicates the importance of intimate surface coating of ZnO with RGO toward the efficiency of enhancement of photoactivity and particularly the anti-photocorrosion of ZnO.