Journal of Applied Physics
115703 (6 pages)
A robust, reproducible method for the extraction of relative bandgap trends from scanning transmission electron microscopy (STEM) based electron energy-loss spectroscopy (EELS) is described. The effectiveness of the approach is demonstrated by profiling the bandgap through a CuIn1-xGaxSe2 solar cell that possesses intentional Ga/(In + Ga) composition variation. The EELS-determined bandgap profile is compared to the nominal profile calculated from compositional data collected via STEM-based energy dispersive X-ray spectroscopy. The EELS based profile is found to closely track the calculated bandgap trends, with only a small, fixed offset difference. This method, which is particularly advantageous for relatively narrow bandgap materials and/or STEM systems with modest resolution capabilities (i.e., 100 meV), compromises absolute accuracy to provide a straightforward route for the correlation of local electronic structure trends with nanoscale chemical and physical structure/microstructure within semiconductor materials and devices. Published by AIP Publishing.
Original Publication Citation
Deitz, J. I., Karki, S., Marsillac, S. X., Grassman, T. J., & McComb, D. W. (2018). Bandgap profiling in CIGS solar cells via valence electron energy-loss spectroscopy. Journal of Applied Physics, 123(11), 115703. doi:10.1063/1.5011658
Deitz, Julia I.; Karki, Shankar; Marsillac, Sylvain X.; and Grassman, Tyler J., "Bandgap Profiling in CIGS Solar Cells Via Valence Electron Energy-Loss Spectroscopy" (2018). Electrical & Computer Engineering Faculty Publications. 149.