Nano-scale SiO2 patterned n-type GaN substrate for 380 nm ultra violet light emitting diodes.

380 nm Ultraviolet (UV) light emitting diodes (LEDs) were grown on patterned n-type GaN substrate (PNS). Wet etched self-assembled indium tin oxide (ITO) nano clusters serves as dry etching mask for converting the SiO2 layer grown on n-GaN template into SiO2 nano dots by inductively coupled plasma etching. In the pre-experiment, crystal quality and optical properties of n-GaN were greatly improved by applying PNS process. In this work, etch-pits density (EPD) method confirmed that PNS with SiO2 nano dots have superior crystalline properties. Thus Reference LED without PNS, 1-step PNS LEDs with SiO2 nano dots size were 200 nm, 250 nm, 300 nm and 300 nm 2-step PNS LED were fabricated. LEDs show almost the same operating voltage of about 3.4 V at an injection current of 50 mA. Light intensity was enhanced by ~2.1 times and 3.2 times for 300 nm 1-step and 300 nm 2-step PNS, respectively. FDTD simulation results show a similar tendency. As a result, PNS promotes epitaxial lateral overgrowth (ELOG) for defect reduction as well as act as a light scattering point.