Rapid thermal annealing effects on vacuum evaporated ITO for InGaN/GaN blue LEDs

8 mil × 10 mil InGaN/GaN blue LEDs with indium tin oxide (ITO) emitting at 460 nm were fabricated. A vacuum evaporation technique was adopted to deposit ITO on P-GaN with thickness of 240 nm. The electrical and optical properties of ITO films on P-GaN wafers, as well as rapid thermal annealing (RTA) effects at different temperatures (100 to 550 °C) were analyzed and compared. It was found that resistivity of 450 °C RTA was as low as 1.19 × 10 −4 Ω·cm, along with a high transparency of 94.17% at 460 nm. AES analysis indicated the variation of oxygen content after 450 °C annealing, and ITO contact resistance showed a minimized value of 3.9 × 10 −3 Ω·cm 2 . With 20 mA current injection, it was found that forward voltage and output power were 3.14 V and 12.57 mW. Furthermore, maximum luminous flux of 0.49 lm of ITO RTA at 550 °C was measured, which is the consequence of a higher transparency.