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) Conductivity and mobility of graphene by direct four-probe measurements via van der Pauw geometry. (a)–(c): Measured resistance by setup-1, setup-2, and setup-3, respectively. Curves from configurations I1_V23 and I2_V34 are indicated by blue and red colors, respectively. (d): Conductivity of the graphene flake in Fig. 2 calculated from the three setups. The fact that the three curves nearly coincide with each other demonstrates the homogeneity of transport properties of this graphene flake. (e): Extracted hole and electron mobility for the three setups.