Texture-engineered fabrication of ultraflat, 6-inch single-crystal Cu(111) wafers
Jiaxin Shao, Yeshu Zhu, Junhao Liao, Shuang Lou, Shiwei Wang, Qimeng Zhang, Yunsong Ge, Mingyue Wei, Zhaoning Hu, Mingtong Zhu, Ge Chen, Sheng Li, Yixuan Zhao, Shiyong Wang, Jincan Zhang, Wei Wei, Nianpeng Lu, Xiucai Sun, Li Lin, Kaicheng Jia, Zhongfan Liu
Abstract
Ultraflat, single-crystal Cu(111) thin films are widely regarded as ideal epitaxial substrates for synthesizing two-dimensional single crystals for ease of subsequent transfer and device integration. However, the fabrication of Cu(111) remains hindered by a lack of scalable and reliable technique to eliminate in-plane twin boundaries (TBs) in final films. Here, we present a method to address TB issues for harvesting ultraflat, TB-free Cu(111) wafers, which also enable the growth of high-quality, single-crystal graphene wafers. It has been revealed that the deposition of Cu films with designed texture would enable the selective abnormal grain growth of specific Cu(111) during high-temperature annealing, allowing for the production of 6-inch TB-free Cu(111) wafers with high crystallinity (misorientation angle of 0.48°), flatness ( R a = 0.34 nm), and scalability (25 wafers per batch). As-harvested graphene exhibits excellent electronic quality and wafer-scale uniformity, with an average carrier mobility of 10,093 square centimeters per volt per second and sheet resistance of 905 ohm per square with 3.5% deviation over entire wafer.