Characterisation of Photocathodes Based on Pb Thin Film Deposited by UV Pulsed Laser Ablation

This work deals with the deposition of lead (Pb) thin films by the UV pulsed laser ablation technique, for their further use as photocathode devices in superconducting radio frequency guns. Scanning electron microscopy and atomic force microscopy analyses were performed to study the morphological features of Pb thin films deposited on Si (100) and Nb substrates. The films showed a granular structure with a nearly fully covered surface only for that one deposited on Nb substrate. X-ray diffraction measurements indicate the growth of polycrystalline Pb thin films with a preferential orientation along (111) planes. Results of the photoemission performance of Pb thin film deposited on Nb substrate showed a very encouraging average value of quantum efficiency of 6 × 10−5 through a single-photon absorption process, promoting further studies in the realisation of Pb photocathodes by this technique.