Field ion microscopy of nanometer-size pyramid grown on a blunt end of tungsten tip

We fabricated nanometer-size pyramids with three {211} -facet sides (nanopyramids) on bluntWtip and observed their atomic structures by field ion microscopy (FIM). The blunt W tip was preliminary subjected to remolding treatment in order to sharpen its end. Owing to the atomic resolution of FIM, we found that the {211} and {110} planes faceted markedly as a result of the remolding treatment and clearly detected the neighboring {211} and {110} planes were separated by a monoatomic chain along the 111 direction. In addition, the (111) plane was raised and narrowed owing to the faceting of the three surrounding {211} planes. Dimension of the narrowed (111) plane was about 3 nm. By using the surface of the remolded-tip end as a substrate, we grew the nanopyramid by depositing Pd atoms and elevating the sample temperature to 1000 K. The FIM observation indicated typical signs for the nanopyramid growth such as markedly-faceted {211} planes, monoatomic linear chains for the pyramid ridge, and extremely narrow top of the pyramid. In this study, the top was the third layer of the ideal nanopyramid counting from the top. Along with previous field emission data [E. Rokuta, T. Nakagawa, H. Murata, S. Fujita, H. Shimoyama, and C. Oshima, Jpn. J. Appl. Phys. 50, 115001 (2011).], the remolding treatment was proven to be useful for the nanopyramid growth on the blunt end of the W tip.