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Title: Development of a cost effective surface-patterned transparent conductive coating as top-contact of light emitting diodes

Sol-gel process has been used to form indium zinc oxide films using an optimized combination of zinc to indium concentration in the precursor solutions. Different structures, like one (1D) and two-dimensional (2D) gratings and diffractive optical elements (DOEs) in the form of Fresnel lens are fabricated on the film surface of proposed top metal contact of LED by imprint soft lithography technique. These structures can enhance the LED's light extraction efficiency (LEE) or can shape the output beam pattern, respectively. Several characterizations are done to analyze the material and structural properties of the films. The presence of 1D and 2D gratings as well as DOEs is confirmed from field emission scanning electron and atomic force microscopes analyses. Although, X-ray diffraction shows amorphous nature of the film, but transmission electron microscopy study shows that it is nano crystalline in nature having fine particles (∼8 nm) of hexagonal ZnO. Shrinkage behaviour of gratings as a function of curing temperature is explained by Fourier transform infra-red spectra and thermo gravimetric-differential thermal analysis. The visible transmission and sheet resistance of the sample are found comparable to tin doped indium oxide (ITO). Therefore, the film can compete as low cost substitute of ITO as top metalmore » contact of LEDs.« less
Authors:
 [1] ;  [2] ; ;  [3] ; ;  [1]
  1. Department of Applied Optics and Photonics, University of Calcutta, Kolkata-700009 (India)
  2. (India)
  3. Sol-Gel Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032 (India)
Publication Date:
OSTI Identifier:
22275515
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 115; Journal Issue: 19; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; 77 NANOSCIENCE AND NANOTECHNOLOGY; ATOMIC FORCE MICROSCOPY; COMPARATIVE EVALUATIONS; CONCENTRATION RATIO; DIFFERENTIAL THERMAL ANALYSIS; DOPED MATERIALS; FIELD EMISSION; FOURIER TRANSFORMATION; FRESNEL LENS; INDIUM OXIDES; LIGHT EMITTING DIODES; NANOSTRUCTURES; SOL-GEL PROCESS; SURFACES; THIN FILMS; TIN COMPOUNDS; TRANSMISSION ELECTRON MICROSCOPY; VISIBLE RADIATION; X-RAY DIFFRACTION; ZINC; ZINC OXIDES