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Density Profiles in Sputtered Molybdenum Thin Films and Their Effects on Sodium Diffusion in Cu(InxGa1-x)Se2 Photovoltaics: Preprint

Conference ·
OSTI ID:1018872
Molybdenum (Mo) thin films were sputtered onto soda lime glass (SLG) substrates. The main variable in the deposition parameters, the argon (Ar) pressure pAr, was varied in the range of 6 - 20 mTorr. Ex situ spectroscopic ellipsometry (SE) was performed to find out that the dielectric functions of the Mo films were strongly dependent on pAr, indicating a consistent and significant decrease in theMo film density pMo with increasing pAr. This trend was confirmed by high-angle-annular-dark-field scanning transmission electron microscopy. Dielectric functions of Mo were then found to be correlated with secondary ion mass spectroscopy profiles of Sodium (Na) in the Cu(InxGa1-x)Se2 (CIGS) layer grown on top of Mo/SLG. Therefore, in situ optical diagnostics can be applied for processmonitoring and optimization in the deposition of Mo for CIGS solar cells. Such capability is demonstrated with simulated optical transmission and reflectance of variously polarized incident light, using dielectric functions deduced from SE.
Research Organization:
National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
DOE Contract Number:
AC36-08GO28308
OSTI ID:
1018872
Report Number(s):
NREL/CP-5200-50701
Country of Publication:
United States
Language:
English