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Title: Plasmon resonance and perfect light absorption in subwavelength trench arrays etched in gallium-doped zinc oxide film

Near-perfect light absorption in subwavelength trench arrays etched in highly conductive gallium-doped zinc oxide films was experimentally observed in the mid infrared regime. At wavelengths corresponding to the resonant excitation of surface plasmons, up to 99% of impinging light is efficiently trapped and absorbed in the periodic trenches. Scattering cross sectional calculations reveal that each individual trench acts like a vertical split ring resonator with a broad plasmon resonance spectrum. The coupling of these individual plasmon resonators in the grating structure leads to enhanced photon absorption and significant resonant spectral linewidth narrowing. Ellipsometry measurements taken before and after device fabrication result in different permittivity values for the doped zinc oxide material, indicating that localized annealing occurred during the plasma etching process due to surface heating. Simulations, which incorporate a 50 nm annealed region at the zinc oxide surface, are in a good agreement with the experimental results.
Authors:
; ;  [1] ;  [1] ;  [2] ;  [1] ;  [2] ;  [3]
  1. Air Force Research Laboratory, Sensors Directorate, 2241 Avionics Circle, Wright Patterson AFB, Ohio 45433 (United States)
  2. (United States)
  3. Department of Electrical and Computer Engineering, University of Alabama in Huntsville, 301 Sparkman Drive, Huntsville, Alabama 35899 (United States)
Publication Date:
OSTI Identifier:
22486043
Resource Type:
Journal Article
Resource Relation:
Journal Name: Applied Physics Letters; Journal Volume: 107; Journal Issue: 19; Other Information: (c) 2015 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ABSORPTION; ANNEALING; DOPED MATERIALS; FILMS; GALLIUM; GRATINGS; PERIODICITY; PERMITTIVITY; PLASMONS; SIMULATION; SPLIT-RING RESONATORS; VISIBLE RADIATION; WAVELENGTHS; ZINC OXIDES