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280 nm Emission Deep UV LEDs with Integrated Fresnel Microlenses

Published online by Cambridge University Press:  01 February 2011

Mikhail E Gaevski ,
Maxim Shatalov ,
Shuai Wu  and
Asif M Khan
Mikhail E Gaevski
Affiliation:
gaevski@engr.sc.edu, University of South Carolina, Electrical Engineering, 301 Main Street, room 3A79,, Department of Electrical Engineering, Columbia, South Carolina, 29208, United States, (803)7778023, (803)7772447
Maxim Shatalov
Affiliation:
shatalov@engr.sc.edu, University of South Carolina, Columbia, 29208, United States
Shuai Wu
Affiliation:
WUSHUAI@engr.sc.edu, University of South Carolina, Columbia, 29208, United States
Asif M Khan
Affiliation:
asif@engr.sc.edu, University of South Carolina, Columbia, 29208, United States
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Abstract

We report on the integration of flowable oxide based Fresnel microlenses with AlGaN based 280 nm light emitting diodes (LED). The lenses were fabricated on the back side of the LED sapphire substrates using direct electron beam writing. Ten concentric rings with different width and variable thickness were designed for 360 degree phase correction. Within each ring the thickness was varied in five steps to approximate a linear profile. The width of each thickness step varied from 100 nm to several microns. Outer diameter of the lens was 65μm. A focal distance of 68 μm was measured for the fabricated microlenses. At the focal plane a FWHM of intensity profile as small as 14 μm was measured for lenses integrated with 30 μm diameter UV LEDs . The maximum intensity at focal plane exceeded the background radiation by a factor of 50. Comparison of the LED performance before and after the lens fabrication did not reveal any degradation of integral efficiency of devices. These results demonstrate the feasibility of using flowable oxide Fresnel microlenses in optical systems based on micro-pixel deep UV AlGaN LEDs.

Keywords

nitridefilmscanning electron microscopy (SEM)
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 916: Symposium DD – Solid-State Lighting Materials and Devices , 2006 , 0916-DD05-09
Copyright
Copyright © Materials Research Society 2006

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