1 January 1994 The FIR tunnel ionization of deep impurities in semiconductors
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Proceedings Volume 2250, International Conference on Millimeter and Submillimeter Waves and Applications 1994; 225071 (1994) https://doi.org/10.1117/12.2303270
Event: Millimeter and Submillimeter Waves and Applications: International Conference, 1994, San Diego, CA, United States
We report on the first observation of the photoionization of deep impurity levels in a semiconductor by FIR radiation with photon energies much less than the ionization energy of impurities. The photoconductivity of gold and mercury doped germanium has been observed and investigated using a high power pulsed FIR laser source. A photoconductive signal, rising exponentially with the incident power, could be detected in spite of the fact that the photon energy of the exciting radiation is several factors of ten less than the binding energy of the impurities, Ei. The experimental results give strong evidence that the ionization of deep impurity centers by radiation with photon energy hw « Ei, is caused by tunnel ionization in the strong optical field. This optical method allows the investigation of the tunnelling process at electric bias fields well below the threshold of avalanche breakdown. It has been previously shown that the thermal emission of deeply bound electrons becomes possible in an electric field due to a phonon assisted tunnel effect even if kgT < Ei [1]. Tunnel ionization has been extensively studied in semiconductors subjected to static electric fields [1-5]. Here we show that such process may occur in an optical field of frequency co < cov, where coy is the local vibration frequency at the impurity site.
© (1994) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
S. D. Ganichev, S. D. Ganichev, } "The FIR tunnel ionization of deep impurities in semiconductors", Proc. SPIE 2250, International Conference on Millimeter and Submillimeter Waves and Applications 1994, 225071 (1 January 1994); doi: 10.1117/12.2303270; https://doi.org/10.1117/12.2303270

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