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

Journal Article · Wed May 21 04:00:00 EDT 2014 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4876737· OSTI ID:22275515

Haldar, Arpita ^[1]; Bera, Susanta; Jana, Sunirmal ^[2]; Bhattacharya, Kallol; Chakraborty, Rajib ^[1]

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1. Department of Applied Optics and Photonics, University of Calcutta, Kolkata-700009 (India)
2. Sol-Gel Division, CSIR-Central Glass and Ceramic Research Institute, Kolkata 700032 (India)

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 metal contact of LEDs.

• OSTI ID: 22275515
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 19 Vol. 115; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

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