Centre for Graphene Science, College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, United Kingdom.
Nano Lett. 2015 Jul 8;15(7):4429-33. doi: 10.1021/acs.nanolett.5b00772. Epub 2015 Jun 23.
Few layer graphene systems such as Bernal stacked bilayer and rhombohedral (ABC-) stacked trilayer offer the unique possibility to open an electric field tunable energy gap. To date, this energy gap has been experimentally confirmed in optical spectroscopy. Here we report the first direct observation of the electric field tunable energy gap in electronic transport experiments on doubly gated suspended ABC-trilayer graphene. From a systematic study of the nonlinearities in current versus voltage characteristics and the temperature dependence of the conductivity, we demonstrate that thermally activated transport over the energy-gap dominates the electrical response of these transistors. The estimated values for energy gap from the temperature dependence and from the current voltage characteristics follow the theoretically expected electric field dependence with critical exponent 3/2. These experiments indicate that high quality few-layer graphene are suitable candidates for exploring novel tunable terahertz light sources and detectors.
少层石墨烯体系，如 Bernal 堆叠双层和三方（ABC-）堆叠三层，为提供可开启电场可调谐能隙的独特可能性。迄今为止，该能隙已在光学光谱学中得到实验证实。在这里，我们报告了在双门控悬浮 ABC-三层石墨烯的电子输运实验中首次直接观察到电场可调谐能隙。通过对电流与电压特性的非线性和电导率随温度的变化的系统研究，我们证明了在能隙上的热激活输运主导了这些晶体管的电响应。从温度依赖性和电流电压特性得出的能隙估计值遵循理论上预期的电场依赖性，具有临界指数 3/2。这些实验表明，高质量的少层石墨烯是探索新型可调谐太赫兹光源和探测器的合适候选材料。
