Integrated wafer-scale ultra-flat graphene by gradient surface energy modulation.

Gao, Xin; Zheng, Liming; Luo, Fang; Qian, Jun; Wang, Jingyue; Yan, Mingzhi; Wang, Wendong; Wu, Qinci et al. · Nat Commun · 2022

basic_science · Level V

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Abstract

The integration of large-scale two-dimensional (2D) materials onto semiconductor wafers is highly desirable for advanced electronic devices, but challenges such as transfer-related crack, contamination, wrinkle and doping remain. Here, we developed a generic method by gradient surface energy modulation, leading to a reliable adhesion and release of graphene onto target wafers. The as-obtained wafer-scale graphene exhibited a damage-free, clean, and ultra-flat surface with negligible doping, resulting in uniform sheet resistance with only ~6% deviation. The as-transferred graphene on SiO<sub>2</sub>/Si exhibited high carrier mobility reaching up ~10,000 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>, with quantum Hall effect (QHE) observed at room temperature. Fractional quantum Hall effect (FQHE) appeared at 1.7 K after encapsulation by h-BN, yielding ultra-high mobility of ~280,000 cm<sup>2</sup> V<sup>-1</sup> s<sup>-1</sup>. Integrated wafer-scale graphene thermal emitters exhibited significant broadband emission in near-infrared (NIR) spectrum. Overall, the proposed methodology is promising for future integration of wafer-scale 2D materials in advanced electronics and optoelectronics.