DGIST Scholar: Work function tuning and fluorescence enhancement of hydrogen annealed Ag-doped Al-rich zinc oxide nanostructures using a sol-gel process

Division of Energy Technology 1. Journal Articles

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Work function tuning and fluorescence enhancement of hydrogen annealed Ag-doped Al-rich zinc oxide nanostructures using a sol-gel process

Title: Work function tuning and fluorescence enhancement of hydrogen annealed Ag-doped Al-rich zinc oxide nanostructures using a sol-gel process

Author Keywords: Thin films ; Sol-gel process ; Work function ; Absorption ; Optical band-gap

Keywords: ABSORPTION ; Aluminum ; AZO Films ; CELL APPLICATION ; Charge Difference ; Energy Gap ; Fluorescence ; Fluorescence Enhancement ; Fluorescence Properties ; Impurity Defects ; Ions ; Maximal Values ; Nanostructured Films ; Optical Band-Gap ; Optical Band Gaps ; Oxide Films ; Passivation ; Photocatalytic Activities ; Photoluminescence Properties ; Semiconductor Doping ; SemICONDUCTORS ; Silver ; Sol-Gel Process ; SURFACE ; THIN-FILMS ; Thin Films ; Work Function ; Work Function Tuning ; Zinc ; Zinc Oxide ; Zinc Oxide Nanostructures ; ZnO

Abstract: Effect of incorporation of Ag on the structural, optical, electrical, and fluorescence properties of sol-gel derived Al-rich zinc oxide (ZnO:Al:Ag) nanostructured films was studied. The Eg of the film slightly decreased to a minimal value with Ag doping, and was found to be about 3.65 eV for RAg/Zn = 1% from its initial value of 3.72 eV (RAg/Zn = 0%). The WF sudden increased to a maximal value of 5.12 eV with Ag doping (for RAg/Zn = 1%) from its initial value of 4.73 eV for RAg/Zn = 0% due to substitution of Ag into Zn sites until saturation was achieved (RAg/Zn = 1%). After more Ag doping, WF started to decrease and finally, reached a value of 4.81 eV for RAg/Zn = 3% because of the formation of an impurity-defect energy level below the intrinsic Fermi level of ZnO. With Ag-doping, the current increased up to RAg/Zn = 1% due to the increase in carrier density. For RAg/Zn = 3% doping, the current density started to increase due to the influence of metallic Ag. The defective peak position was blue shifted, with increased Ag-doping, from 536 nm (RAg/Zn = 1%) to 527 nm for RAg/Zn = 2% due to the sizes of the Ag+ and Zn2+ ions. The FL defective peak intensity (ID) in the green region increased with the concentration of Ag used for doping, up to RAg/Zn = 2%. The enhancement in the ID may be due to charge difference between the Zn2+ ions, caused by Ag+ ions. © 2015 Elsevier B.V. All rights reserved.