Direct measurements of conductivity and mobility in millimeter-sized single-crystalline graphene via van der Pauw geometry

Ma Rui-Song^{1, 2, 3}, Huan Qing^{1, 2, 3}, Wu Liang-Mei^{1, 2, 3}, Yan Jia-Hao^{1, 2, 3}, Zhang Yu-Yang², Bao Li-Hong^{1, 2, 3, †}, Liu Yun-Qi⁴, Du Shi-Xuan^{1, 2, 3}, Gao Hong-Jun^{1, 2, 3, ‡}

(color online) Schematic diagrams of direct four-probe measurements on graphene via van der Pauw geometry. (a): Schematic diagram of four-probe measurement by setup-1. Probe 1 and 2 contact two nearest corners while probe 3 and 4 contact the corners on the opposite side. (b)–(c): Schematic diagrams of setup-2 and setup-3, respectively. The rectangles formed by the probes in these two setups are rotated relative to that in setup-1 with −2π/3 and 2π/3, respectively.