This paper shows a fast process control for reactive deposition of semiconductor chalcogen compounds,such as CIG(S,Se) absorbers and S-based buffer layers (Indium or Zinc Sulphides).A Plasma Emission Monitoring (P.E.M.) based feedback control is implemented for high precision control of the chalcogen species.The chalcogenides are injected in the plasma in vapour phase by means of a pulsed valve cracker effusion cell.The metal-to-chalcogen balance can be tuned and stabilized for long deposition times,thus obtaining high deposition rates and precise control of the film stoichiometry,this is crucial for obtaining high efficiency devices.A single step and stable sputtering process for CIGS thin film solar absorbers that could improve process yields and reduce product cost is presented.