Excitation spectroscopy of thin-film disordered semiconductors

S. Q. Gu; P. Craig Taylor; Jim T. McKinley; Akira Ueda; X. Yang; Norman H. Tolk

doi:10.1117/12.148030

14 July 1993 Excitation spectroscopy of thin-film disordered semiconductors

S. Q. Gu, P. Craig Taylor, Jim T. McKinley, Akira Ueda, X. Yang, Norman H. Tolk

Proceedings Volume 1854, Free-Electron Laser Spectroscopy in Biology, Medicine, and Materials Science; (1993) https://doi.org/10.1117/12.148030
Event: OE/LASE'93: Optics, Electro-Optics, and Laser Applications in Scienceand Engineering, 1993, Los Angeles, CA, United States

Abstract

In this paper we examine the use of a high-power, tunable free-electron laser (FEL) source to measure photoluminescence (PL) and photoluminescence excitation (PLE) spectra in two classes of disordered semiconductors, amorphous semiconductors and partially ordered III-V ternary semiconductors. The source must be tunable to follow the absorption continuously across the region of the optical energy gap, and the source must be of high power to provide enough absorbed photons in this relatively transparent spectral region so that PL processes can be measured. The usefulness of PLE spectroscopy in these semiconducting thin films lies in the fact that if the quantum efficiency (eta) for the PL process is independent of energy, then the PLE spectrum is a measure of the optical absorption. In addition, disordered semiconductors often exhibit enhanced absorption below the optical gap due to the disorder itself. PLE measurements that probe regions where the absorption coefficient (alpha) is small ((alpha) < < 10³ cm^-1) are most important because in these regions (alpha) is dominated by the electronic states introduced by the disorder.

Citation Download Citation

S. Q. Gu, P. Craig Taylor, Jim T. McKinley, Akira Ueda, X. Yang, and Norman H. Tolk "Excitation spectroscopy of thin-film disordered semiconductors", Proc. SPIE 1854, Free-Electron Laser Spectroscopy in Biology, Medicine, and Materials Science, (14 July 1993); https://doi.org/10.1117/12.148030

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