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.