Light extraction enhancement of GaN-based LEDs through passive/active photon recycling

In this paper, we present a study of light extraction of GaN-based LEDs through active/passive photon recycling, including sapphire-based and Thin-GaN based on Monte Carlo ray tracing. The mechanisms in enhancing light extraction incorporated with implanting micro pyramid (lens) array and lens encapsulation of both cavity photon recycling and quantum photon recycling are discussed. For an absorption coefficient of 200 cm− 1 in the active layer, both approaches perform more than 90% of light extraction efficiency through cavity photon recycling. For a heavy absorbed active layer, the quantum photon recycling could play an important role in light extraction.