Fabrication of photonic crystal structures on light emitting diodes by nanoimprint lithography

Photonic crystal (PC) structures on green light emitting diodes (LED) were successfully fabricated using nanoimprint lithography. The stamp, with a two-dimensional pillar structure, was fabricated using laser interference lithography through a double exposure technique. To achieve PC structures with a precise dimension, thermal treatment of the photoresist was employed during stamp fabrication; this proved to be effective for the control of the diameter and shape of the hole. The two-dimensional PC structures, with a period of 295 nm, diameter of 180 nm and depth of 100 nm, on the green LEDs resulted in nine-fold enhancement of the photoluminescence intensity compared to the as-deposited samples without PC structures.