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

• Published in: NPJ 2D materials and applications Vol. 7; no. 1; pp. 72 - 7
• Main Authors: Xiong, Fangzhu, Sun, Jie, Tang, Penghao, Guo, Weiling, Dong, Yibo, Du, Zaifa, Feng, Shiwei, Li, Xuan
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 19-10-2023; Nature Publishing Group; Nature Portfolio
• Subjects: 639/925/918; 639/925/927; Chemical vapor deposition; Chemistry and Materials Science; Contact resistance; Controllability; Electrodes; Etching; Gallium nitrides; Graphene; Heat; Materials Science; Mesas; Nanotechnology; Semiconductor devices; Spreaders; Surfaces and Interfaces; Thermal resistance; Thin Films
• ISSN: 2397-7132; 2397-7132
• DOI: 10.1038/s41699-023-00434-9

A technique for the transfer-free growth of 2-inch wafer-scale patterned graphene directly on GaN LED epilayers is introduced. High-quality graphene as transparent electrodes and heat spreaders is synthesized directly on GaN by PECVD at only 600 °C deposition temperature and within 3 min growth time. Co acts as both the catalyst for graphene growth and the dry etching mask for GaN mesas, which greatly improves the efficiency of the semiconductor device process. Elegantly, the graphene growth is in accordance with the shape of Co, which offers a lithography-free patterning technique of the graphene. Afterward, using our penetration etching method through the PMMA and graphene layers, the Co is peacefully removed, and in-situ Ohmic contact is achieved between the graphene and p-GaN where the contact resistivity is only 0.421 Ω cm
2
. The graphene sheet resistance is as low as 631.2 Ω sq
−1
. The device is also superior to the counterpart graphene-free LED in terms of heat spreading behavior, as evidenced by the lower junction temperature and thermal resistance. Most importantly, the developed technique produces graphene with excellent performance and is intrinsically more scalable, controllable, and semiconductor industry compatible than traditionally transferred graphene.