27 June 2019 Improved light extraction efficiency of complementary metal-oxide semiconductor hot carrier lights sources with the use of improved back-end-of-line light directing structures
Anthony F. Bulling, Petrus J. Venter
Author Affiliations +
Abstract
Previous research has shown that the use of back-end-of-line (BEOL) light directing structures with silicon hot carrier light sources in a complementary metal-oxide semiconductor results in improved light extraction efficiency. This work focuses on the design of an improved back-end-of-line structure for improving light extraction efficiency when using substrate-based silicon light emitters. With the use of FRED optical engineering ray-tracing software, it was found that a significant amount of generated light is lost at the material interfaces of the optical structure, including losses due to significant internal reflections. Therefore, an optimized optical structure was designed to reduce internal reflections at the base of the structure. Simulation results show a 33.6% improvement in light extraction efficiency over the previously designed parabolic optical structure, over the visible spectrum. The light sources were tested using a parameter analyzer, radiometer, spectrometer, and goniometer. It was calculated that the luminance exiting the optimized optical structure had a 55.66-factor improvement over the control structure and a 1.35-factor improvement over the parabolic structure. Furthermore, the optimized structure had a 1.38-factor improvement in light extraction efficiency over the parabolic structure. Overall, the improved designed pipe-like BEOL light directing structure helped to improve the device luminescence and light emission direction from the light source, which invariably increased the light extraction efficiency.
© 2019 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2019/$25.00 © 2019 SPIE
Anthony F. Bulling and Petrus J. Venter "Improved light extraction efficiency of complementary metal-oxide semiconductor hot carrier lights sources with the use of improved back-end-of-line light directing structures," Optical Engineering 58(6), 065105 (27 June 2019). https://doi.org/10.1117/1.OE.58.6.065105
Received: 11 February 2019; Accepted: 10 June 2019; Published: 27 June 2019
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Cited by 3 scholarly publications.
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KEYWORDS
Light

Back end of line

Light sources

Geometrical optics

Semiconductors

Ray tracing

Structural design

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