Jiang Yan, Guo Wanlin
Institute of Nano Science, Nanjing University of Aeronautics and Astronautics, No 29 Yu-Dao Street, Nanjing 210016, People's Republic of China.
Nanotechnology. 2008 Aug 27;19(34):345302. doi: 10.1088/0957-4484/19/34/345302. Epub 2008 Jul 15.
Convex and concave nanodots were created on highly oriented pyrolytic graphite (HOPG) in ambient air by applying a voltage pulse between a metal-coated atomic force microscope (AFM) tip and the sample surface. Using a linear scan with a positive substrate bias, nanoscale lines were also etched on the HOPG surface. Depending on the amplitude and duration of the voltage pulse, the nanostructures are either convex or concave. The depth of the concave structure sharply increased with the amplitude and duration of the voltage pulse, while the height of the convexity stayed at a low level and varied in a small range with the voltage lower than a threshold value. Under negative substrate bias or in a vacuum, no change occurred on the HOPG surface in the experimental range. The formation of the nanostructures can be ascribed to the primary dissociative adsorption of water and oxygen in air induced by the intensive hole concentration and the subsequent defect-assisted oxidation of graphite.
通过在金属涂层原子力显微镜（AFM）针尖与样品表面之间施加电压脉冲，在环境空气中于高度定向热解石墨（HOPG）上制备了凸形和凹形纳米点。使用具有正衬底偏压的线性扫描，还在HOPG表面蚀刻出纳米级线条。根据电压脉冲的幅度和持续时间，纳米结构要么是凸形的，要么是凹形的。凹形结构的深度随着电压脉冲的幅度和持续时间急剧增加，而当电压低于阈值时，凸形高度保持在较低水平且在小范围内变化。在负衬底偏压下或真空中，在实验范围内HOPG表面没有变化。纳米结构的形成可归因于由强空穴浓度诱导的空气中水和氧的初级解离吸附以及随后石墨的缺陷辅助氧化。
