J. T. Sullivan, Regan G. Wilks, M. T. Winkler, Lothar Weinhardt, D. Recht, A. J. Said, B. K. Newman, Y. Zhang, Monika Blum, S. Krause, Wan Li Yang, Clemens Heske, M. J. Aziz, Marcus Bär, T. Buonassisi
- 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.