Fabrication of Coherent Electron Sources with Palladium Oxide Reservoirs

Abstract

Tungsten (W) nanopyramids coated with noble metal films can function as highly coherent electron sources. This study aims to grow nanopyramids by employing long-distance surface diffusion of palladium (Pd) atoms. Collodion (also known as nitrocellulose) containing PdO powder was coated on the regions far from the W tip and was used as a source of Pd atoms. Annealing the W tip in UHV resulted in a change in the field ion microscopy (FIM) pattern. The resultant FIM images showed three equivalent {211} planes adjacent to the {111} planes of the W tips. However, with the proposed method, the apex of the W tip was not a single atom, but a wide triangle corresponding to the subsurface of an ideal nanopyramid.