title: Soft X-ray Spectroscopy of a Complex Heterojunction in High-Efficiency Thin-Film Photovoltaics: Intermixing and Zn Speciation at the Zn(O,S)/Cu(In,Ga)Se2Interface.
abstract: The chemical structure of the Zn(O,S)/Cu(In,Ga)Se2interface in high-efficiency photovoltaic devices is investigated using X-ray photoelectron and Auger electron spectroscopy, as well as soft X-ray emission spectroscopy. We find that the Ga/(Ga+In) ratio at the absorber surface does not change with the formation of the Zn(O,S)/Cu(In,Ga)Se2interface. Furthermore, we find evidence for Zn in multiple bonding environments, including ZnS, ZnO, Zn(OH)2, and ZnSe. We also observe dehydrogenation of the Zn(O,S) buffer layer after Ar+ion treatment. Similar to high-efficiency CdS/Cu(In,Ga)Se2devices, intermixing occurs at the interface, with diffusion of Se into the buffer, and the formation of S-In and/or S-Ga bonds at or close to the interface.
authors.affiliation: Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , Las Vegas, Nevada 89154-4003, United States.
authors.forename: Michelle
authors.initials: M
authors.lastname: Mezher
authors.affiliation: National Renewable Energy Laboratory (NREL) , Golden, Colorado 80401, United States.
authors.forename: Rebekah
authors.initials: R
authors.lastname: Garris
authors.affiliation: National Renewable Energy Laboratory (NREL) , Golden, Colorado 80401, United States.
authors.forename: Lorelle M
authors.initials: LM
authors.lastname: Mansfield
authors.affiliation: Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , Las Vegas, Nevada 89154-4003, United States.
authors.forename: Monika
authors.initials: M
authors.lastname: Blum
authors.affiliation: Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT) , 76344 Eggenstein-Leopoldshafen, Germany.|Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , 76128 Karlsruhe, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Hauschild
authors.affiliation: Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , Las Vegas, Nevada 89154-4003, United States.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Horsley
authors.affiliation: Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , Las Vegas, Nevada 89154-4003, United States.
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Duncan
authors.affiliation: Advanced Light Source, Lawrence Berkeley National Laboratory , Berkeley, California 94720, United States.
authors.forename: Wanli
authors.initials: W
authors.lastname: Yang
authors.affiliation: Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , Las Vegas, Nevada 89154-4003, United States.|Renewable Energy, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH , 14109 Berlin, Germany.|Institut für Physik und Chemie, Brandenburgische Technische Universität Cottbus-Senftenberg , 03046 Cottbus, Germany.
authors.forename: Marcus
authors.initials: M
authors.lastname: Bär
authors.affiliation: Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , Las Vegas, Nevada 89154-4003, United States.|Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT) , 76344 Eggenstein-Leopoldshafen, Germany.|Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , 76128 Karlsruhe, Germany.
authors.forename: Lothar
authors.initials: L
authors.lastname: Weinhardt
authors.affiliation: National Renewable Energy Laboratory (NREL) , Golden, Colorado 80401, United States.
authors.forename: Kannan
authors.initials: K
authors.lastname: Ramanathan
authors.affiliation: Department of Chemistry and Biochemistry, University of Nevada, Las Vegas (UNLV) , Las Vegas, Nevada 89154-4003, United States.|Institute for Photon Science and Synchrotron Radiation (IPS), Karlsruhe Institute of Technology (KIT) , 76344 Eggenstein-Leopoldshafen, Germany.|Institute for Chemical Technology and Polymer Chemistry (ITCP), Karlsruhe Institute of Technology (KIT) , 76128 Karlsruhe, Germany.
authors.forename: Clemens
authors.initials: C
authors.lastname: Heske
keywords: X-ray emission spectroscopy; X-ray photoelectron spectroscopy; Zn(O,S); alternative buffer layers; chalcopyrite thin-film solar cell; chemical structure