Field electron emission from molybdenum platinum alloy tips

Through annealing at 900-1000 K under ultrahigh vacuum, a nanopyramid terminated by a single atom was spontaneously grown on a Mo-Pt alloy tip surface. We observed single-atom termination of the pyramid by field ion microscopy and detected its characteristic features by field emission spectroscopy. Mo95%-Pt5% alloy tips were fabricated into single-atom terminated pyramids at a higher success rate than were Mo99%-Pt1% alloy tips, strongly suggesting that Pt segregation at the tip surface was crucial for single-atom termination. In addition, we found the Mo95%-Pt5% alloy tips to be self-repairing and demountable, which are common properties in single-atom termination of body-centered cubic metal tips covered with a face-centered cubic material.