DocumentCode :
43357
Title :
Transparent Back Contacts for Superstrate (Ag,Cu)(In,Ga)Se 
Thin Film Solar Cells
Author :
Simchi, H. ; Larsen, J.K. ; Shafarman, W.N.
Author_Institution :
Inst. of Energy Conversion, Univ. of Delaware, Newark, DE, USA
Volume :
5
Issue :
1
fYear :
2015
fDate :
Jan. 2015
Firstpage :
406
Lastpage :
409
Abstract :
Molybdenum oxide (MoO3) and tungsten oxide (WO3) are considered as transparent back contacts for (Ag,Cu)(In,Ga)Se2 thin film solar cells. MoO3 and WO3 films were deposited by reactive RF sputtering at room temperature in an Ar/O2 ambient on (Ag,Cu)(In,Ga)Se2 absorber layers with various Ga/(Ga + In) and Ag/(Ag + Cu) ratios. Determination of the valence band offsets by XPS showed that Ag-alloying of absorber layer changes the energy band alignment at the absorber-back contact interface with MoO3 and WO3 contacts. This produces a primary contact with lower valence band offset compared with Cu(In,Ga)Se2 counterparts. The effect is less significant in films with Ga > 0.5 and Ag > 0.5 (corresponding to Eg > 1.4 eV) probably due to the different nature of ordered vacancy compounds forming near the surface phases.
Keywords :
X-ray photoelectron spectra; copper compounds; gallium compounds; indium compounds; molybdenum compounds; semiconductor growth; semiconductor thin films; silver compounds; solar cells; sputter deposition; tungsten compounds; vacancies (crystal); valence bands; (AgCu)(InGa)Se2-MoO3; (AgCu)(InGa)Se2-WO3; XPS; absorber layers; absorber-back contact interface; energy band alignment; ordered vacancy compounds; reactive RF sputtering; superstrate thin film solar cells; surface phases; temperature 293 K to 298 K; transparent back contacts; valence band offset; Gallium; Photonic band gap; Photovoltaic cells; Photovoltaic systems; Sputtering; Back contact; XPS; oxide; solar cell;
fLanguage :
English
Journal_Title :
Photovoltaics, IEEE Journal of
Publisher :
ieee
ISSN :
2156-3381
Type :
jour
DOI :
10.1109/JPHOTOV.2014.2365469
Filename :
6957516
Link To Document :
