Fabrication of single atom emitters prepared by using surface diffusion of noble metals

We have developed a new method for preparing atomic-scale pyramids with three {211}-facet sides (nanopyramids) applied for single-atom emitters (SAEs). In the present method, atoms were electroplated only on the backward faces of the W tip, and supplied forward via surface diffusion promoted by elevating temperatures to 1000 K in UHV. With additional annealing at the same temperature, the tip end was covered with thin metal layers, and the nanopyramids were found to spontaneously grow. Opening angles of the FE electron beams were approximately ±2 °. The present nanopyramids yielded FE fluctuations of about 1 %, which were lower than those exhibited by the nanopyramid produced with the previous electroplating method and comparable to those with vacuum deposition method.