Plasmon resonance and perfect light absorption in subwavelength trench arrays etched in gallium-doped zinc oxide film
Abstract
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.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Nov 09, 2015
- Source ID
- 10.1063/1.4935219
Entities
People
- Joshua R Hendrickson
- Junpeng Guo
- Justin W. Cleary
- Kevin Leedy
- Nima Nader
- Shivashankar Vangala
Organizations
- Air Force Office of Scientific Research
- Air Force Research Laboratory
- National Science Foundation
- University of Alabama in Huntsville