Improvement of brightness with Al2O3 passivation layers on the surface of InGaN/GaN-based light-emitting diode chips

In this study, sputtered 50, 70 and 90 nm thick Al₂O₃ thin films were evaluated as a passivation layer in the process of InGaN-based blue as LEDs (Light-Emitting Diodes) in order to improve the brightness of LED lamps. For packaged LED lamps, lamps with Al₂O₃ passivation layer had higher brightness than ones with SiO₂ passivation layer, and LED lamps with 90-nm Al₂O₃ passivation layer were the brightest among four kinds of lamps. Although lamps with Al₂O₃ passivation layer had a bias voltage 0.25 V at 20 mA forward current higher the lamps built with SiO₂ passivation layer, their brightness was improved about 13.6% higher than the conventional LEDs with no change in emitting wavelength.