Strong Enhancement in Light Output of GaN-Based LEDs With Graded-Refractive-Index ITO Deposited on Textured V-Shaped Pits

An interesting structure of GaN-based light-emitting diodes (LEDs) with different indium-tin-oxide (ITO) films deposited on naturally textured V-shaped pits (V-pits) is fabricated and studied. The sputtered ITO assists the textured surface to get a better contact and thus reduces the forward voltage. Moreover, the ITO films prepared by different methods can serve as graded-refractive-index antireflective coatings, which can enhance the performance of the V-pits LED further. The results show that the V-pits LED with two layers ITO films have a stronger light output power than the reference LED by 52.1% at 20 mA, and the forward voltage is only a little higher than the standard LED.