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. Photocathodes based on Mg and Y thin films have been characterized by scanning electron microscopy and x-ray diffraction techniques to derive the morphological and structural features, respectively. They were also tested in a photodiode cell to deduce the photoelectron properties. The quantum efficiency of such photocathodes was systematically improved by in~situ laser cleaning treatments of the surface in order to remove the contaminated layers reaching, in this way, the quantum efficiency of the corresponding bulk materials.

Pb thin films were deposited on Nb substrates by means of pulsed laser deposition (PLD) with UV radiation (248 nm), in two different ablation regimes: picosecond (5 ps) and subpicosecond (0.5 ps). Granular films with grain size on the micron scale have been obtained, with no evidence of large droplet formation. All films presented a polycrystalline character with preferential orientation along the (111) crystalline planes. A maximum quantum efficiency (QE) of $7.3\times {10}^{-5}$ (at 266 nm and 7 ns pulse duration) was measured, after laser cleaning, demonstrating good photoemission performance for Pb thin films deposited by ultrashort PLD. Moreover, Pb thin film photocathodes have maintained their QE for days, providing excellent chemical stability and durability. These results suggest that Pb thin films deposited on Nb by ultrashort PLD are a noteworthy alternative for the fabrication of photocathodes for superconductive radio-frequency electron guns. Finally, a comparison with the characteristics of Pb films prepared by ns PLD is illustrated and discussed.