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 ℃) were analyzed and compared.It was found that resistivity of 450 ℃ 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 ℃ annealing,and ITO contact resistance showed a minimized value of 3.9 × 10-3 Ω·cm2.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 ℃ was measured,which is the consequence of a higher transparency.
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