TY - GEN A1 - Sullivan, J. T. A1 - Wilks, Regan G. A1 - Winkler, M. T. A1 - Weinhardt, Lothar A1 - Recht, D. A1 - Said, A. J. A1 - Newman, B. K. A1 - Zhang, Y. A1 - Blum, Monika A1 - Krause, S. A1 - Yang, Wan Li A1 - Heske, Clemens A1 - Aziz, M. J. A1 - Bär, Marcus A1 - Buonassisi, T. T1 - Soft x-ray emission spectroscopy studies of the electronic structure of silicon supersaturated with sulfur N2 - 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. KW - black silicon KW - solar cells KW - electronic surface structure KW - x-ray emission spectroscopy Y1 - 2011 ER - TY - GEN A1 - Bär, Marcus A1 - Schubert, Björn-Arvid A1 - Marsen, Björn A1 - Wilks, Regan G. A1 - Blum, M. A1 - Krause, S. A1 - Pookpanratana, Sujitra A1 - Zhang, Y. A1 - Unold, Thomas A1 - Yang, W. A1 - Weinhardt, Lothar A1 - Heske, Clemens A1 - Schock, Hans-Werner T1 - Cu2ZnSnS4 thin-film solar cell absorbers illuminated by soft x-rays T2 - Journal of Materials Research N2 - 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. Y1 - 2012 U6 - https://doi.org/10.1557/jmr.2012.59 SN - 2044-5326 VL - 27 IS - 8 SP - 1097 EP - 1104 ER - TY - GEN A1 - Blum, M. A1 - Odelius, Michael A1 - Weinhardt, Lothar A1 - Pookpanratana, Sujitra A1 - Bär, Marcus A1 - Zhang, Y. A1 - Fuchs, Oliver A1 - Yang, W. A1 - Umbach, Eberhard A1 - Heske, Clemens T1 - Ultrafast Proton Dynamics in Aqueous Amino Acid Solutions Studied by Resonant Inelastic Soft X‑ray Scattering T2 - The Journal of physical chemistry : B N2 - 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. Y1 - 2012 SN - 1520-5207 VL - 116 IS - 46 SP - 13757 EP - 13764 ER - TY - GEN A1 - Duncan, Douglas A. A1 - Kephart, Jason M. A1 - Horsley, Kimberly A1 - Blum, Monika A1 - Mezher, Michelle A1 - Weinhardt, Lothar A1 - Häming, Marc A1 - Wilks, Regan G. A1 - Hofmann, Timo A1 - Yang, Wanli A1 - Bär, Marcus A1 - Sampath, Walajabad S. A1 - Heske, Clemens T1 - Characterization of sulfur bonding in CdS:O buffer layers for CdTe-based thin-film solar cells T2 - ACS Applied Materials & Interfaces Y1 - 2015 U6 - https://doi.org/10.1021/acsami.5b03503 SN - 1944-8244 SN - 1944-8252 VL - 7 IS - 30 SP - 16382 EP - 16386 ER - TY - GEN A1 - Mezher, Michelle A1 - Garris, Rebekah A1 - Mansfield, Lorelle M. A1 - Horsley, Kimberly A1 - Weinhardt, Lothar A1 - Duncan, Douglas A. A1 - Blum, Monika A1 - Rosenberg, Samantha G. A1 - Bär, Marcus A1 - Ramanathan, Kannan A1 - Heske, Clemens T1 - Electronic structure of the Zn(O,S)/Cu(In,Ga)Se₂ thin-film solar cell interface T2 - Progress in Photovoltaics: Research and Applications Y1 - 2016 U6 - https://doi.org/10.1002/pip.2764 SN - 1099-159X VL - 24 IS - 8 SP - 1142 EP - 1148 ER - TY - GEN A1 - Mezher, Michelle A1 - Garris, Rebekah A1 - Mansfield, Lorelle M. A1 - Blum, Monika A1 - Hauschild, Dirk A1 - Horsley, Kimberly A1 - Duncan, Douglas A. A1 - Yang, Wooyong A1 - Bär, Marcus A1 - Weinhardt, Lothar A1 - Ramanathan, Kannan A1 - Heske, Clemens T1 - 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 T2 - ACS Applied Materials & Interfaces Y1 - 2016 U6 - https://doi.org/10.1021/acsami.6b09245 SN - 1944-8244 VL - 8 IS - 48 SP - 33256 EP - 33263 ER -