Transfer-free rapid growth of 2-inch wafer-scale patterned graphene as transparent conductive electrodes and heat spreaders for GaN LEDs

This paper introduces a transfer-free technique for growing 2-inch wafer-scale patterned graphene directly on GaN LED epilayers. High-quality graphene, serving as transparent electrodes and heat spreaders, is synthesized directly on GaN using PECVD at 600°C for only 3 minutes. Cobalt (Co) acts as both the catalyst for graphene growth and the dry etching mask for GaN mesas, enhancing process efficiency. Graphene growth conforms to the Co pattern, enabling lithography-free patterning. A penetration etching method removes Co, creating in-situ Ohmic contact between graphene and p-GaN with a contact resistivity of 0.421 Ωcm². The graphene sheet resistance is as low as 631.2 Ωsq⁻¹. The resulting device demonstrates superior heat spreading compared to graphene-free LEDs, evidenced by lower junction temperature and thermal resistance. This technique offers scalability, controllability, and semiconductor industry compatibility.

Fangzhu Xiong, Jie Sun, Penghao Tang, Weiling Guo, Yibo Dong, Zaifa Du, Shiwei Feng, Xuan Li