Wu Zefei, Han Yu, Huang Rui, Chen Xiaolong, Guo Yanqing, He Yuheng, Li Wei, Cai Yuan, Wang Ning
Department of Physics, the Hong Kong University of Science and Technology, Hong Kong, China.
Nanoscale. 2014 Nov 7;6(21):13196-202. doi: 10.1039/c4nr03183k.
We demonstrate that a reversible semimetallic-to-metallic transition can be realized in monolayer graphene by iodine doping and dedoping processes. Upon iodine doping, the charge transfer from graphene to iodine creates a high hole density up to 4.75 × 10(13)cm(-2), well beyond that realized by applying gate voltages. Iodine-doped graphene shows metallic behaviour, as evidenced by the resistance variation with temperature and magnetic field. We further introduce an iodine dedoping method to completely remove the iodine anions from graphene surfaces. Transport measurements show that after dedoping treatments, the mobility of graphene is significantly enhanced, much higher than that of pristine graphene. The improvement in graphene electronic properties is attributed to the corrosive characteristic of iodine that it can react with and remove absorbed atoms on graphene surfaces. Our work not only opens a facile and effective way to tune the properties of monolayer graphene reversibly, but also demonstrates a new method to increase the quality of graphene.
我们证明，通过碘掺杂和去掺杂过程，可以在单层石墨烯中实现可逆的半金属到金属的转变。在碘掺杂时，从石墨烯到碘的电荷转移产生了高达4.75×10¹³ cm⁻²的高空穴密度，远超过通过施加栅极电压所实现的空穴密度。碘掺杂的石墨烯表现出金属行为，这通过电阻随温度和磁场的变化得到证实。我们进一步引入了一种碘去掺杂方法，以完全从石墨烯表面去除碘阴离子。输运测量表明，去掺杂处理后，石墨烯的迁移率显著提高，远高于原始石墨烯。石墨烯电子性质的改善归因于碘的腐蚀性，即它可以与石墨烯表面吸附的原子反应并将其去除。我们的工作不仅为可逆地调节单层石墨烯的性质开辟了一种简便有效的方法，而且还展示了一种提高石墨烯质量的新方法。
