Patent ID: 8536773

Claim:
A source, comprising: a base; a tip fixed to the base and extending from the base, the tip comprising: a core having a surface comprising a first material; and a coating on the core, the coating comprising a second material, the second material forming a surface of the tip, and the second material comprising more than 30% by weight of a lanthanide element; a first electrical terminal electrically connected to the coating; an extraction electrode having an opening; and a second electrical terminal electrically connected to the extraction electrode, wherein: the source is an electron beam source, and the first material is different from the second material; and at least one of the following conditions is fulfilled: an electrical conductivity of the first material is less than 10 5 S/m; and a ratio of the electrical conductivity of the second material to the electrical conductivity of the first material is greater than 10:1.