Device for controlling electron flow and method for manufacturing said device

A method for manufacturing a device for controlling electron flow, the method comprising the steps of:

• providing at least one elongate electrical conductor in electrical communication with a cathode;
• embedding the or each said conductor in a substrate comprising diamond;
• providing an anode, wherein the or each said conductor is adapted to emit electrons from an end thereof remote from the cathode through the substrate to the anode;
• providing at least one control electrode for modifying the electric field in the region of the end of the or each said electrical conductor;
• and
• providing at least one layer of insulating material, wherein the or each control electrode is separated from the or each said conductor by said insulating material, and wherein at least one said control electrode has at least one first aperture arranged such that electrons emitted from the end of the or each said conductor remote from the cathode pass through a said first aperture to said anode.