Near atomically smooth alkali antimonide photocathode thin films

• DOI: 10.1063/1.4974363
• Publication Date: 2017-01-24T16:13:53Z
• Authors: Jun Feng; Siddharth Karkare; James Nasiatka; Susanne Schubert; John Smedley; Howard Padmore
• Keywords: Accelerator Physics (physics.acc-ph); FOS: Physical sciences; 02 engineering and technology; 01 natural sciences; Mathematical Sciences; Engineering; Physical Sciences; 0103 physical sciences; Physics - Accelerator Physics; 0210 nano-technology; physics.acc-ph; Applied Physics

Nano-roughness is one of the major factors degrading the emittance of electron beams that can be generated by high efficiency photocathodes, such as the thermally reacted alkali antimonide thin films. In this paper, we demonstrate a co-deposition based method for producing alkali antimonide cathodes that produce near atomic smoothness with high reproducibility. We calculate the effect of the surface roughness on the emittance and show that such smooth cathode surfaces are essential for operation of alkali antimonide cathodes in high field, low emittance radio frequency electron guns and to obtain ultracold electrons for ultrafast electron diffraction applications.