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

Jian Li, Stephen Glynn, Lorelle Mansfield, Matthew Young, Yanfa Yan, Miguel Contreras, Rommel Noufi, Fred Lewis Terry, Dean Levi

Research output: Contribution to conferencePaperpeer-review

8 Scopus Citations

Abstract

Molybdenum (Mo) thin films were sputtered onto soda lime glass (SLG) substrates. The main variable in the deposition parameters, the argon (Ar) pressure p Ar, was varied in the range of 6 - 20 mTorr. Ex situ spectroscopic ellipsometry (SE) was performed to find out that the dielectric functions ε of the Mo films were strongly dependent on p Ar, indicating a consistent and significant decrease in the Mo film density ρ Mo with increasing p Ar. This trend was confirmed by high-angle-annular-dark-field scanning transmission electron microscopy. ε of Mo was then found to be correlated with secondary ion mass spectroscopy profiles of Sodium (Na) in the Cu(In xGa 1-x)Se 2 (CIGS) layer grown on top of Mo/SLG. Therefore, in situ optical diagnostics can be applied for process monitoring 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 ε deduced from SE.

Original languageAmerican English
Pages2749-2752
Number of pages4
DOIs
StatePublished - 2011
Event37th IEEE Photovoltaic Specialists Conference, PVSC 2011 - Seattle, WA, United States
Duration: 19 Jun 201124 Jun 2011

Conference

Conference37th IEEE Photovoltaic Specialists Conference, PVSC 2011
Country/TerritoryUnited States
CitySeattle, WA
Period19/06/1124/06/11

Bibliographical note

See NREL/CP-5200-50701 for preprint

NREL Publication Number

  • NREL/CP-5200-55734

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