We review the current status of metallic photocathodes based on thin films prepared by
pulsed laser deposition (PLD) and we explore ways to improve the performance of these
devices. PLD seems to be a very efficient and suitable technique for producing adherent and
uniform thin films. Time-resolved mass spectrometric investigations definitively suggest that
the deposition of high-purity metallic thin films should be carried out in ultrahigh vacuum
systems and after a deep and careful laser cleaning of the target surface. Moreover, the laser
cleaning of the target surface is highly recommended not only to remove the first contaminated
layers but also to improve the quality of the vacuum by reducing the partial pressure of reactive
chemical species as H2O, H2, and O2 molecules. The challenge to realize high-purity Mg and Y
thin films is very interesting for the photocathode R&D due to the good photoemission
properties of these metals
