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.
Bulling, Anthony F.(University of Pretoria, 2019-02-14)
Silicon light sources allow the integration of both an emissive display and associated electronic circuitry within a monolithic silicon substrate, all within a standard CMOS manufacturing process with the use of a single ...
Gwizdala, Michal; Berera, Rudi; Kirilovsky, Diana; Van Grondelle, Rienk; Kruger, T.P.J. (Tjaart)(American Chemical Society, 2016-09)
When exposed to intense sunlight all organisms performing oxygenic photosynthesis implement various photoprotective strategies to prevent potentially lethal photodamage. The rapidly responding photoprotective mechanisms, ...