Study of a GaN-Based LED With an Al/AZO Composite Transparent Conductive Layer

A new and simple Al/aluminum-doped zinc oxide (AZO) composite structure is proposed to act as a transparent conductive layer (TCL) for GaN-based LEDs. The Al/AZO composite layers effectively improve the current spreading performance, compared with an AZO TCL. Experimentally, the specific contact resistance of the studied Al/AZO LED is reduced by about 27.6%, compared with an AZO LED. In addition, under an operating current of 20 mA, the forward voltage and light output power (LOP) of the studied Al/AZO LED are decreased by 0.15 V and increased by 19.5%, respectively. Uniform and enhanced intensities are also found in light emission mapping images of the studied Al/AZO LED. Consequently, based on benefits including simple structure and improved electrical and optical properties, the studied Al/AZO TCL is suitable for GaN-based LED applications.