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

• Published in: IEEE transactions on electron devices 2017-09, Vol.64 (9), p.3678-3682
• Main Authors: Hsu, Chi-Hsiang, Chen, Sheng-Yi, Chen, Wei-Cheng, Chang, Ching-Hong, Chen, Chun-Yen, Tsai, Jung-Hui, Liu, Wen-Chau
• Format: Article
• Language: English
• Subjects: Al/AZO composite layers; Aluminum; Conductivity; Contact resistance; Electric contacts; Emission analysis; Gallium nitrides; GaN LED; Image enhancement; Light emitting diodes; light output power (LOP); Luminous intensity; mapping images; Metals; Optical devices; Optical imaging; Optical properties; Performance evaluation; Resistance; transparent conductive layer (TCL); Zinc oxide
• ISSN: 0018-9383; 1557-9646
• DOI: 10.1109/TED.2017.2724599

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.