Light Extraction Efficiency and Radiation Patterns of III-Nitride Light-Emitting Diodes With Colloidal Microlens Arrays With Various Aspect Ratios

Xiao-Hang Li; Renbo Song; Yik-Khoon Ee; Pisist Kumnorkaew; James F. Gilchrist; Nelson Tansu

doi:10.1109/JPHOT.2011.2150745

IEEE Photonics Journal (Jan 2011)

Light Extraction Efficiency and Radiation Patterns of III-Nitride Light-Emitting Diodes With Colloidal Microlens Arrays With Various Aspect Ratios

Xiao-Hang Li,
Renbo Song,
Yik-Khoon Ee,
Pisist Kumnorkaew,
James F. Gilchrist,
Nelson Tansu

Affiliations

Xiao-Hang Li: <formula formulatype="inline"><tex Notation="TeX">$^{1}$</tex></formula>Center for Optical Technologies, Department of Electrical and Computer Engineering, Lehigh University, Bethlehem , PA, USA
Renbo Song: Center for Optical Technologies, Department of Electrical and Computer Engineering, Lehigh University, Bethlehem , PA, USA
Yik-Khoon Ee: Center for Optical Technologies, Department of Electrical and Computer Engineering, Lehigh University, Bethlehem , PA, USA
Pisist Kumnorkaew: <formula formulatype="inline"><tex Notation="TeX">$^{2}$</tex></formula>Department of Chemical Engineering, Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, PA, USA
James F. Gilchrist: Department of Chemical Engineering, Center for Advanced Materials and Nanotechnology, Lehigh University, Bethlehem, PA, USA
Nelson Tansu: Center for Optical Technologies, Department of Electrical and Computer Engineering, Lehigh University, Bethlehem, PA, USA

DOI: https://doi.org/10.1109/JPHOT.2011.2150745
Journal volume & issue: Vol. 3, no. 3
pp. 489 – 499

Abstract

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The fabrication studies of silica/polystyrene (PS) colloidal microlens arrays with various aspect ratios were performed on the III-nitride light-emitting diodes (LEDs). The use of colloidal-based microlens arrays led to significant enhancement in light extraction efficiency for III-nitride LEDs. In varying the aspect ratios of the microlens arrays, the engineering of various PS thicknesses was employed by using high-temperature treatment and redeposition process. The effects of PS thickness on the light extraction efficiency and far-field emission patterns of InGaN quantum-well (QW) LEDs were studied. The total output powers of microlens LEDs with various PS thicknesses exhibited 1.93-2.70 times enhancement over that of planar LEDs, and the use of optimized PS layer thickness is important in leading the enhancement of the light extraction efficiency in large angular direction.

Published in IEEE Photonics Journal

ISSN: 1943-0655 (Online)
Publisher: IEEE
Country of publisher: United States
LCC subjects: Technology: Engineering (General). Civil engineering (General): Applied optics. Photonics; Science: Physics: Optics. Light
Website: http://ieeexplore.ieee.org/xpl/RecentIssue.jsp?punumber=4563994

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