• 
  Bär, M.; Schubert, B.-A.; Marsen, B.; Wilks, R.G.; Pookpanratana, S.; Blum, M.; Krause, S.; Unold, T.; Yang, W.; Weinhardt, L.; Heske, C.; Schock, H.-W.: Cliff-like conduction band offset and KCN-induced recombination barrier enhancement at the CdS/Cu₂ZnSnS₄ thin-film solar cell heterojunction. Applied Physics Letters 99 (2011), p. 222105/1-3

10.1063/1.3663327

Abstract:
The electronic structure of the CdS/Cu2ZnSnS4 (CZTS) heterojunction was investigated by direct and inverse photoemission. The effects of a KCN etch of the CZTS absorber prior to CdS deposition on the band alignment at the respective interface was studied. We find and a “cliff”-like conduction band offset at the CdS/CZTS interface independent of absorber pretreatment. Furthermore, a significant enhancement of the energetic barrier for carrier recombination across the CdS/CZTS interface is observed when the CZTS is etched. Hence, KCN etching opens a route for a deliberate tailoring of the electronic structure in CZTS thin-film solar cells.