@misc{SullivanWilksWinkleretal., author = {Sullivan, J. T. and Wilks, Regan G. and Winkler, M. T. and Weinhardt, Lothar and Recht, D. and Said, A. J. and Newman, B. K. and Zhang, Y. and Blum, Monika and Krause, S. and Yang, Wan Li and Heske, Clemens and Aziz, M. J. and B{\"a}r, Marcus and Buonassisi, T.}, title = {Soft x-ray emission spectroscopy studies of the electronic structure of silicon supersaturated with sulfur}, abstract = {We apply soft x-ray emission spectroscopy (XES) to measure the electronic structure of crystalline silicon supersaturated with sulfur (up to 0.7 at. \%), a candidate intermediate-band solar cell material. Si L2,3 emission features are observed above the conventional Si valence band maximum, with intensity scaling linearly with S concentration. The lineshape of the S-induced features change across the insulator-to-metal transition, indicating a significant modification of the local electronic structure concurrent with the change in macroscopic electronic behavior. The relationship between the Si L2,3 XES spectral features and the anomalously high sub-band gap infrared absorption is discussed.}, language = {en} } @misc{BaerSchubertMarsenetal., author = {B{\"a}r, Marcus and Schubert, Bj{\"o}rn-Arvid and Marsen, Bj{\"o}rn and Wilks, Regan G. and Blum, M. and Krause, S. and Pookpanratana, Sujitra and Zhang, Y. and Unold, Thomas and Yang, W. and Weinhardt, Lothar and Heske, Clemens and Schock, Hans-Werner}, title = {Cu2ZnSnS4 thin-film solar cell absorbers illuminated by soft x-rays}, series = {Journal of Materials Research}, volume = {27}, journal = {Journal of Materials Research}, number = {8}, issn = {2044-5326}, doi = {10.1557/jmr.2012.59}, pages = {1097 -- 1104}, abstract = {In view of the complexity of thin-film solar cells, which are comprised of a multitude of layers, interfaces, surfaces, elements, impurities, etc., it is crucial to characterize and understand the chemical and electronic structure of these components. Because of the high complexity of the Cu2ZnSn(S,Se)4 compound semiconductor absorber material alone, this is particularly true for kesterite-based devices. Hence, this paper reviews our recent progress in the characterization of Cu2ZnSnS4 (CZTS) thin films. It is demonstrated that a combination of different soft x-ray spectroscopies is an extraordinarily powerful method for illuminating the chemical and electronic material characteristics from many different perspectives, ultimately resulting in a comprehensive picture of these properties. The focus of the article will be on secondary impurity phases, electronic structure, native oxidation, and the CZTS surface composition.}, language = {en} } @misc{BlumOdeliusWeinhardtetal., author = {Blum, M. and Odelius, Michael and Weinhardt, Lothar and Pookpanratana, Sujitra and B{\"a}r, Marcus and Zhang, Y. and Fuchs, Oliver and Yang, W. and Umbach, Eberhard and Heske, Clemens}, title = {Ultrafast Proton Dynamics in Aqueous Amino Acid Solutions Studied by Resonant Inelastic Soft X‑ray Scattering}, series = {The Journal of physical chemistry : B}, volume = {116}, journal = {The Journal of physical chemistry : B}, number = {46}, issn = {1520-5207}, pages = {13757 -- 13764}, abstract = {Resonant inelastic soft X-ray scattering (RIXS) has been used to study the electronic structure of glycine and lysine in aqueous solution. Upon variation of the pH value of the solution from acidic to basic, major changes of the nitrogen K edge RIXS data are observed for both amino acids, which are associated with the protonation and deprotonation of the amino groups. The experimental results are compared with simulations based on density functional theory, yielding a detailed understanding of the spectral changes, as well as insights into the ultrafast proton dynamics in the intermediate core-excited/ionized state of the RIXS process.}, language = {en} } @misc{DuncanKephartHorsleyetal., author = {Duncan, Douglas A. and Kephart, Jason M. and Horsley, Kimberly and Blum, Monika and Mezher, Michelle and Weinhardt, Lothar and H{\"a}ming, Marc and Wilks, Regan G. and Hofmann, Timo and Yang, Wanli and B{\"a}r, Marcus and Sampath, Walajabad S. and Heske, Clemens}, title = {Characterization of sulfur bonding in CdS:O buffer layers for CdTe-based thin-film solar cells}, series = {ACS Applied Materials \& Interfaces}, volume = {7}, journal = {ACS Applied Materials \& Interfaces}, number = {30}, issn = {1944-8244}, doi = {10.1021/acsami.5b03503}, pages = {16382 -- 16386}, language = {en} } @misc{MezherGarrisMansfieldetal., author = {Mezher, Michelle and Garris, Rebekah and Mansfield, Lorelle M. and Horsley, Kimberly and Weinhardt, Lothar and Duncan, Douglas A. and Blum, Monika and Rosenberg, Samantha G. and B{\"a}r, Marcus and Ramanathan, Kannan and Heske, Clemens}, title = {Electronic structure of the Zn(O,S)/Cu(In,Ga)Se₂ thin-film solar cell interface}, series = {Progress in Photovoltaics: Research and Applications}, volume = {24}, journal = {Progress in Photovoltaics: Research and Applications}, number = {8}, issn = {1099-159X}, doi = {10.1002/pip.2764}, pages = {1142 -- 1148}, language = {en} } @misc{MezherGarrisMansfieldetal., author = {Mezher, Michelle and Garris, Rebekah and Mansfield, Lorelle M. and Blum, Monika and Hauschild, Dirk and Horsley, Kimberly and Duncan, Douglas A. and Yang, Wooyong and B{\"a}r, Marcus and Weinhardt, Lothar and Ramanathan, Kannan and Heske, Clemens}, 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)Se2 interface}, series = {ACS Applied Materials \& Interfaces}, volume = {8}, journal = {ACS Applied Materials \& Interfaces}, number = {48}, issn = {1944-8244}, doi = {10.1021/acsami.6b09245}, pages = {33256 -- 33263}, language = {en} }