采用紧束缚格林函数法研究原子吸附石墨烯纳米带电子输运  

Electronic Transport Properties of Atom Adsorption Graphene Nanoribbon Devices Based on Tight Binding Green's Function Method

作　　者：李昕[1] 张永[1] 殷德民[1] 王小力[1] 刘卫华[1] 

机构地区：[1]西安交通大学电子与信息工程学院,西安710049

出　　处：《西安交通大学学报》2015年第2期37-42,61,共7页Journal of Xi'an Jiaotong University

基　　金：国家自然科学基金资助项目(91123018;61172041;61172040);陕西省自然科学基金资助项目(2014JM7277)

摘　　要：采用紧束缚非平衡格林函数法分析了扶手椅型石墨烯纳米带(AGNR)和锯齿形石墨烯纳米带(ZGNR)器件吸附H、F、O和OH这4种原子的电子输运特性。用π电子结构体系的紧束缚理论分析了GNR的电子结构;用紧束缚扩展休克理论计算了GNR碳原子与所吸附原子间的电子相互作用;用非平衡格林函数法仿真了GNR吸附原子后的电流特性。研究结果表明:在平衡态下,AGNR吸附H原子后对器件的输运谱影响最大,而吸附OH原子后使GNR的禁带宽度增加0.3eV;在非平衡态下,吸附H原子不仅增加了导带底附近态密度,而且直接在禁带引入了杂质能级,从而提高了AGNR器件产生的电流;H原子吸附在ZGNR器件产生的电流约是吸附在AGNR电流的1.5倍;H原子吸附在GNR非边界处比吸附在边界处产生的电流高。该研究结果可以对提高石墨烯气敏传感器和生物传感器的灵敏度提供理论基础。Electron transport properties of four kinds of atoms H, F, O and OH to adsorb armchair graphene nanoribbons （AGNR） and zigzag graphene nanoribbons （ZGNR） device are studied by using the tight binding non equilibrium Green function method. The electronic structure of GNR is analyzed using the tight binding theory of n electron structure. The electronic interaction among adsorbed atoms and GNR carbon atoms is calculated based on the expansion shock theory. The current characteristics of GNR adsorbing atoms are calculated using the non equilibrium Green function. The results show that the adsorption of H atoms has the greatest impact on the AGNR device transport spectrum in four kinds of atoms and the adsorption of OH atoms increases 0.3 eV of band gap at an equilibrium state, and that the current from H atom adsorption is larger than that of the other atoms at a non equilibrium state, because H atom adsorption not only increases density of states near the bottom of the conduction band, but also introduces impurity energy level in the band gap directly. The current from H atoms in ZGNR is 1.5 times higher than that from AGNR and the current of H atomic adsorption in middle of GNRis higher than that of its edge. The results provide a theoretical basis for improving the sensitivity of graphene gas sensors and biosensors.

关 键 词：石墨烯纳米带 原子吸附 紧束缚 格林函数 输运谱 

分 类 号：TN304.9[电子电信—物理电子学]