Potential of CuS cap to prevent decomposition of Cu2ZnSnS4 during annealing
2015 (English)In: Physica Status Solidi (a) applications and materials science, ISSN 1862-6300, E-ISSN 1862-6319, Vol. 212, no 12, 2843-2849 p.Article in journal (Refereed) Published
One of the challenges associated with processing of Cu2ZnSnS4 (CZTS) is the thermal decomposition reaction that causes loss of S and SnS from the absorber surface. To reduce the decomposition a sufficiently high SnS and S partial pressure must be supplied during annealing. The absorber surface can alternatively be protected with a thin cap. Aiming to obtain a more flexible process, CZTS precursors were capped with a thin CuS layer before annealing. The cap was subsequently removed with a KCN etch before device finishing. It was found that the cap coverage decreased during annealing, exposing a part of the absorber surface. At the same time, the initially Cu poor absorber took up Cu from the cap, ending up with a stoichiometric Cu content. Devices made from capped precursors or precursors annealed without sulfur had poor device characteristics. An increased doping density of almost one order of magnitude could be the reason for the very poor performance. CuS is therefore not a suitable cap material for CZTS. Other cap materials could be investigated to protect the CZTS absorber surface during annealing.
Place, publisher, year, edition, pages
2015. Vol. 212, no 12, 2843-2849 p.
cap layer;Cu2ZnSnS4;kesterite;solar cells;thin films
Condensed Matter Physics Engineering and Technology
IdentifiersURN: urn:nbn:se:uu:diva-263983DOI: 10.1002/pssa.201532420ISI: 000366589900028OAI: oai:DiVA.org:uu-263983DiVA: diva2:858868
FunderSwedish Research CouncilSwedish Foundation for Strategic Research EU, FP7, Seventh Framework Programme, 316488