کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
79344 | 49353 | 2011 | 6 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Optical analysis of the microstructure of a Mo back contact for Cu(In,Ga)Se2 solar cells and its effects on Mo film properties and Na diffusivity Optical analysis of the microstructure of a Mo back contact for Cu(In,Ga)Se2 solar cells and its effects on Mo film properties and Na diffusivity](/preview/png/79344.png)
The microstructures of molybdenum (Mo) thin films deposited at pressures from 3.3 to 10.3 mTorr were characterized, and the relationships between these microstructures and the properties of the films (residual stress and electrical resistivity) were investigated. In the low deposition pressure regime (region I, below 7 m Torr), the residual stress in the tensile direction increases with increasing pressure and the electrical resistivity increases gradually, but at high deposition pressures (region II, above 7 m Torr) the residual stress is reduced and the resistivity increases more steeply. These variations of the properties of the Mo films in the low pressure regime are due to the variation in grain size; the carrier mobility decreases due to increased grain boundary (GB) scattering and the tensile stress increases due to increased atomic attraction across the GBs. In contrast, the porosity of the Mo films increases significantly in the high pressure regime, as demonstrated with variable angle spectroscopic ellipsometry (VASE). Most of these pores are believed to be present along the grain boundaries of the Mo films, so their presence reduces the GB attraction and thus the tensile stress and enhances the carrier scattering. The high porosity of the Mo back contact was shown with secondary ion mass spectroscopy profiling to accelerate the Na diffusion from soda-lime glass into the Cu(In,Ga)Se2 (CIGS) film.
Graphical AbstractFigure optionsDownload as PowerPoint slideResearch highlights
► We applied the spectroscopic ellipsometry to estimate the porosity of Mo back contacts for CIGS solar cells.
► Mo films showed different microstructural features respectively in the regimes of low and high working pressure.
► The electrical and mechanical properties of Mo could be understood in terms of their microstructures.
► The porous Mo back contact enhances Na diffusion into the CIGS films from SLG.
Journal: Solar Energy Materials and Solar Cells - Volume 95, Issue 11, November 2011, Pages 2959–2964