Microstructure characterization of Mo back contact used for CIGS based solar cell

Two separate series of Mo thin films were deposited on Si/SiO2, and soda lime glass (SLG) substrates using direct-current planar magnetron sputtering, with a sputtering power density of 1.2 W/cm². The working gas (Ar) pressure was varied from 0.6 mT to 16 mT to gain a better understanding of the effect of sputtering pressure on the morphology and porosity of the Mo thin films and the subsequent effect on the Na out-diffusion from SLG glass substrates. The morphology of Mo-coated SLG substrates was examined using high-resolution scanning electron microscopy (HRSEM). The porosity of the Mo films as a function of sputtering pressure was studied by transmission electron microscopy (TEM) on Mo-coated Si/SiO2 substrates. Secondary-ion mass spectrometry (SIMS) was applied to depth profile the Na in as-deposited Mo/SLG substrates.