title: From GaN to ZnGa(2)O(4) through a low-temperature process: nanotube and heterostructure arrays.
abstract: We demonstrate a method to synthesize GaN-ZnGa2O4 core-shell nanowire and ZnGa2O4 nanotube arrays by a low-temperature hydrothermal process using GaN nanowires as templates. Transmission electron microscopy and X-ray photoelectron spectroscopy results show that a ZnGa2O4 shell forms on the surface of GaN nanowires and that the shell thickness is controlled by the time of the hydrothermal process and thus the concentration of Zn ions in the solution. Furthermore, ZnGa2O4 nanotube arrays were obtained by depleting the GaN core from GaN-ZnGa2O4 core-shell nanowire arrays during the reaction and subsequent etching with HCl. The GaN-ZnGa2O4 core-shell nanowires exhibit photoluminescence peaks centered at 2.60 and 2.90 eV attributed to the ZnGa2O4 shell, as well as peaks centered at 3.35 and 3.50 eV corresponding to the GaN core. We also demonstrate the synthesis of GaN-ZnGa2O4 heterojunction nanowires by a selective formation process as a simple route toward development of heterojunction nanodevices for optoelectronic applications.
authors.affiliation: Department of Materials Science and Engineering, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States.
authors.forename: Ming-Yen
authors.initials: MY
authors.lastname: Lu
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhou
authors.forename: Cheng-Yao
authors.initials: CY
authors.lastname: Chiu
authors.forename: Samuel
authors.initials: S
authors.lastname: Crawford
authors.forename: Silvija
authors.initials: S
authors.lastname: Gradečak
mesh_terms: D003080:Cold Temperature; D005708:Gallium / Q000737:chemistry*; D043942:Nanotubes / Q000737:chemistry*; D053770:Nanowires / Q000737:chemistry*; D010316:Particle Size; D012825:Silicon / Q000737:chemistry; D013696:Temperature; D015034:Zinc Oxide / Q000737:chemistry
chemical_list: D005708:Gallium; D015034:Zinc Oxide; D012825:Silicon