Process for preparing a metal containing layer, the process comprising (i) at least one step of co-vaporization, at a pressure which is lower than 10−2 Pa, of a) at least one first metal selected from Li, Na, K, Rb and Cs and b) at least one second metal selected Mg, Zn, Hg, Cd and Te from a metal alloy provided in a first vaporization source which is heated to a temperature between 100° C. and 600° C., and (ii) at least one subsequent step of deposition of the first metal on a surface having a temperature which is below the temperature of the first vaporization source, wherein in step (i), the alloy is provided at least partly in form of a homogeneous phase comprising the first metal and the second metal, electronic devices comprising such materials and process for preparing the same.