Light Output Enhancement of InGaN Light-Emitting Diodes Grown on Masklessly Etched Sapphire Substrates

A maskless wet-etching method is used to prepare patterned sapphire substrates for enhancing the output power of InGaN light-emitting diodes (LEDs). Blue LEDs grown on the patterned sapphire substrates exhibit an output power of 24.9 mW, which is 19.4% higher than that of the devices grown on flat substrates. The uniformity of the optical and electrical properties of LEDs across a 2-in wafer is slightly improved as well.