Shaina P R, Sakorikar Tushar, Sarkar Biporjoy, Kavitha M K, Vayalamkuzhi Pramitha, Jaiswal Manu
Department of Physics, Indian Institute of Technology Madras, Chennai 600036, India.
J Phys Condens Matter. 2017 Jun 14;29(23):235301. doi: 10.1088/1361-648X/aa6eba.
We investigate temperature-dependent charge transport in reduced graphene oxide (rGO) films coated on flexible polydimethylsiloxane (PDMS) substrates which are subject to uniaxial strain. Variable strain, up to 10%, results in an anisotropic morphology comprising of quasi-periodic linear array of deformations which are oriented perpendicular to the direction of strain. The anisotropy is reflected in the charge transport measurements, when conduction in the direction parallel and perpendicular to the applied strain are compared. Temperature dependence of resistance is measured for different values of strain in the temperature interval 80-300 K. While the resistance increases significantly upon application of strain, the temperature-dependent response shows anomalous decrease in resistance ratio R /R upon application of strain. This observation of favorable conduction processes under strain is further corroborated by reduced activation energy analysis of the temperature-dependent transport data. These anomalous transport features can be reconciled based on mutually competing effects of two processes: (i) thinning of graphene at the sites of periodic deformations, which tends to enhance the overall resistance by a purely geometrical effect, and (ii) locally enhanced inter-flake coupling in these same regions which contributes to improved temperature-dependent conduction.
我们研究了涂覆在柔性聚二甲基硅氧烷（PDMS）基底上的还原氧化石墨烯（rGO）薄膜中的温度依赖性电荷传输，该基底承受单轴应变。高达10%的可变应变导致一种各向异性形态，其由垂直于应变方向排列的准周期性线性变形阵列组成。当比较平行和垂直于施加应变方向的传导时，各向异性反映在电荷传输测量中。在80 - 300 K的温度区间内，针对不同应变值测量了电阻的温度依赖性。虽然施加应变时电阻显著增加，但应变作用下温度依赖性响应显示电阻比R /R出现反常下降。通过对温度依赖性传输数据的活化能分析降低，进一步证实了应变下有利传导过程的这一观察结果。这些反常传输特征可以基于两个过程相互竞争的效应来解释：（i）周期性变形部位石墨烯的变薄，这倾向于通过纯粹的几何效应提高整体电阻；（ii）这些相同区域中局部增强的片间耦合，这有助于改善温度依赖性传导。
