Research Initiation Award Grant Investigation of Doping in Graphene

该项目的总体目标是在维尔京群岛大学建立材料科学研究文化，并为加强这一本科院校的研究和教育一体化基础设施作出贡献。该项目的研究目标是了解石墨烯的掺杂机制，进行退火研究，以调查是否可以修改石墨烯的微结构，以确定在器件应用中导致材料中更持久的掺杂效应的条件，并通过计算建模和模拟发展定量的理解。对石墨烯电化学和电子掺杂机理的研究将促进对石墨烯在电子和传感器器件中的性质的认识。本项目将展示四氟四氰基喹二甲烷(F4-TCNQ)表面修饰石墨烯的p型掺杂。F4-TCNQ已被广泛应用于有机发光二极管中，通过在金属接触附近形成一个狭窄的空间电荷区来降低空穴注入势垒，从而提高器件性能。因此，用F4-TCNQ修饰石墨烯表面有望促进电子从石墨烯向F4-TCNQ分子的转移，导致F4-TCNQ中的电子积累层和石墨烯中的耗尽层，从而实现石墨烯的p型掺杂。该项目的第二个任务是使用化学气相沉积系统研究过渡金属(TM)作为潜在的电子掺杂剂在石墨烯中的作用。掺杂研究将得到载流子输运测量的补充。该项目旨在找到所需的掺杂量、原子浓度和它们在表面上的排列之间的关系。为了确定掺杂效应是否仍然存在，将进行一系列的退火实验。最后，将确定哪种机制最适合n型和p型掺杂，以及哪组条件最有利于石墨烯保持其掺杂状态。

The overarching goals of this project are to establish a culture of research in materials science at the University of the Virgin Islands, and to contribute to enhancing the infrastructure for integration of research and education at this undergraduate institution. The research objectives of the project are to understand doping mechanisms in graphene, to perform annealing studies to investigate if the microstructure of graphene can be modified to determine conditions that lead to more permanent doping effects in the material for device applications, and to develop a quantitative understanding through computational modeling and simulations. The research on understanding electrochemical and electronic doping mechanisms in graphene will advance the knowledge of properties of graphene for electronic and sensor device applications.This project will demonstrate p-type doping of graphene by surface modification with tetrafluorotetracyanoquinodimethane (F4-TCNQ). F4-TCNQ has been widely used in organic light-emitting diodes to reduce the hole injection barrier by forming a narrow space-charge region near the metal contact, thereby improving device performance. Modifying the graphene surface with F4-TCNQ is therefore expected to favor electron transfer from graphene to F4-TCNQ molecules, leading to an electron accumulation layer in F4-TCNQ and a depletion layer in the graphene, thereby achieving p-type doping of the graphene. The second task of this project is to investigate the effects of transition metals (TM) as potential electronic dopants in graphene using a chemical vapor deposition system. The doping studies will be complimented with carrier transport measurements. The project intends to find a correlation between the desired amount of doping, the concentration of atoms and their arrangement on the surface. A series of annealing experiments will be performed in order to determine whether or not the doping effect is still present. Lastly, it will be determined which mechanism is best suited for n-type and p-type doping and which set of conditions are most favorable for graphene to maintain its doped state.