a: Scanning electron microscope image of the cross section of the film at the end of the first stage. This image shows the morphological layered structure of the film at the end of the first stage. 2b: Qualitative profiles of gallium (in red) and indium (in blue) measured by glow discharge optical emission spectrometry throughout a film at the end of the first stage. This plot shows three different zones corresponding to the layers observed by SEM.