Photoelectron emission from yttrium thin films prepared by pulsed laser deposition

We present the results of our investigation of metallic films as suitable materials for the production of intense electron beams. Thin films of Y prepared for the first time by pulsed laser deposition on Si substrates have been tested as photocathodes in an ultra high vacuum photodiode chamber at 10(-6) Pa. High quantum efficiencies have been obtained for the deposited films, comparable to those of corresponding bulks. The role of the adsorbed gases on the emission performance has been studied. Systematic laser cleaning treatments improved the quantum efficiency (QE) from 10(-6) to 4.5 10(-4). The samples could stay for several months in open air before being tested in a photodiode cell. The deposition process and testing results are presented.