Improved current spreading performance of a GaN-based light-emitting diode with a stair-like ITO layer

• The stair-like ITO structure could effectively improve the current spreading performance.
• The current distribution could be adjusted by the different thickness of each step in stair-like ITO layer.
• The stair-like ITO structure could be formed by the simple wet etching process with standard photolithographic.

A GaN-based light-emitting diode (LED) with a stair-like ITO layer is studied. The stair-like ITO structure is achieved by using a simple wet etching process. The current distribution could be adjusted by the different thickness of each step in this stair-like ITO layer. The current injected from p-pad is forced to be spread outside by the thicker ITO layer below the p-pad, which exhibits larger parasitic series resistance, instead of flowing downward directly. The current spreading effect could be enhanced. As compared with a conventional LED, at 20 mA, the studied device with a stair-like ITO layer shows 13.8% improvement in light output power. A lower turn-on voltage is also achieved.

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