The EDS spectra as illustrated in Fig. 10 revealed an increase in Cu signal at 600 °C, which could possibly, then get oxidized. Images from SEM (Fig. 11) and AFM (Fig 12) displayed an increase in the size of particles, and a slight increase in average surface roughness, respectively. This indicated the thermally activated easy CP 690550 particles during annealing. Furthermore, no voids in the absorber were observed. Formation of voids is generally due to non-uniform distribution of the elements in local micro-regions that leads to the existence of a small impurity phases. Hence, the absence of voids in the AlxOy/Pt/AlxOy MSSAC clearly demonstrated the homogeneous distribution of particles without impurities. Overall, the annealed samples did not exhibit any substantial change from those deposited at room temperature. Consequently, it was established that the substrate temperature did not affect the thermal stability of the AlxOy/Pt/AlxOy MSSAC, which is in agreement with the observation of Glen A. Nyberg et al. .