Optimization and Fabrication of III-Nitride Light-Emitting Diodes with Self-assembled Colloidal-based Convex Microlens Arrays

Improvement of light extraction efficiency of InGaN light emitting diodes (LEDs) using colloidal-based SiO
₂
/ polystyrene microlens arrays was demonstrated. The size effect of the SiO
₂
microspheres and the thickness of the polystyrene layer on the light extraction efficiency were studied. Ray tracing simulations show that the use of microlens arrays leads to increase in light extraction efficiency by 2.6 times. This is consistent with experiments that demonstrated 2.7 times improvement in light extraction utilizing SiO
₂
/polystyrene microlens arrays. The enhancement in light extraction efficiency is attributed to increase in effective photon escape cone due to SiO
₂
/polystyrene microlens arrays.