Overview and development of metallic photocathodes

This work reviews the requirements and the current status of metallic photocathodes. Particular attention is given to yttrium and magnesium which have many advantages respect to copper based photocathode which is generally used in RF photoinjectors. Among the different techniques used to prepare photocathodes based on thin metallic films, pulsed laser ablation deposition has been proposed as a promising technique for realizing photocathodes based on magnesium and yttrium thin films of good quality in terms of high adhesion and chemical composition.