Enhanced Light Extraction from Gan-based Leds with Ps Nanospheres: Nanosphere Layer on Blue Leds and Nano-patterned Sapphire Substrate Leds Fabricated by Nanosphere Lithography

In this book, we have demonstrated the surface roughness and nano-PSS LED fabricated by nanosphere lithography. In surface roughness LED, We have successfully proposed and fabricated GaN-based LEDs with nanosphere layers. The surface texturing process is easily and quickly achieved by using nanosphere layers. This coating of the nanosphere layers does not affect the electrical characteristic of the LED. The periodic structure of nanosphere layers enhances the light extraction efficiency of the LED. The luminance intensities of the LEDs with nanosphere layers of 300 nm and 500 nm diameters were seen to increase by 5.72% and 9.05% at 20 mA, respectively. In nano-PSS LED, the crystalline quality of GaN epilayer was estimated by XRD. The FWHM of nano-PSS LEDs and micro-PSS LEDs were narrower than that conventional LED. This means that we could improve crystal quality of GaN epilayer by using nano-PSS LEDs and micro-PSS. The nano-PSS LED also has better electrical property than conventional LED. The light output power of the nano- PSS LED was 18.8%~25.2%higher than the conventional LED.