A method of monitoring the chalcogenation process in which the chalcogenide semiconductor layer is produced by initially sequentially depositing the two precursor layers of elements A and B and thereafter carrying out a chalcogenizing process with a simultaneous optical process control in which the layer sequence A B is irradiated by light from at least one coherent light source, the light diffusely scattered at the surface is detected and the scattered light signal measured as a function of time is evaluated such that characteristic changes in the layer developing during the chalcogenation are assigned to four characteristic points of the scattered light signal curve.