Observation of enhanced visible and infrared emissions in photonic crystal thin-film light-emitting diodes

– YF Cheung, KH Li, RSY Hui, and HW Choi

FE-SEM image showing the HCP nano-pillar array fabricated by NSL. (b) Schematic diagram (not-to-scale) of the vertical PhC thin-film LED. Microphotographs of the (c) V-PhCLED, (d) V-LED, and (e) L-LED.

Applied Physics Letters, vol. 105, 7, pp. 071104 (2014)

Photonic crystals, in the form of closed-packed nano-pillar arrays patterned by nanosphere lithography, have been formed on the n-faces of InGaN thin-film vertical light-emitting diodes (LEDs). Through laser lift-off of the sapphire substrate, the thin-film LEDs conduct vertically with reduced dynamic resistances, as well as reduced thermal resistances. The photonic crystal plays a role in enhancing light extraction, not only at visible wavelengths but also at infrared wavelengths boosting heat radiation at high currents, so that heat-induced effects on internal quantum efficiencies are minimized. The observations are consistent with predictions from finite-difference time-domain simulations.

DOI: 10.1063/1.4893739