The Enhancement of Phonon Echo Generation by Defects in Crystals

  • D. J. Meredith
  • H. Mkhwanazi
  • J. K. Wigmore
  • T. Miyasato
Conference paper
Part of the Springer Series in Solid-State Sciences book series (SSSOL, volume 51)

Abstract

The amplitudes of backward wave phonon echoes generated in single crystals of piezoelectric and pyroelectric materials are notoriously unreproducible. In a very few experiments it has been possible to correlate the observed anomalies with the presence of clearly identifiable defects. In CdS, for example, a variety of effects are observed which it is believed are due to the presence of shallow donors together with deep double acceptors [1] The non-linearity responsible for the parametric coupling between the primary acoustic wave and the electric field of the microwave pump is an electric field-induced tunnelling of electrons from donor states into the conduction band. The tunnelling probability is proportional to exp{−1/|E|}, where E is the total electric field at the donor, so that the echo amplitude is a very rapid function of the pump power, PM. A second defect mechanism for backward wave echo generation arises through the saturated absorption of two-level systems. This mechanism has been identified as being responsible for backward wave echoeneration by OH defects in glasses [2], and by indium acceptors in silicon [3] The exact power dependence on PM depends on the detailed coupling parameters of the particular transition. Clearly, however, it must be more complicated than a simple linear or quadratic dependence, since the echo power, PE, must tend to zero both at low powers, where the transition is not saturated at all, and at high powers where the populations are equalised.

Keywords

Quartz Microwave Attenuation Acoustics 

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References

  1. 1.
    N. S. Shiren and R. L. Melcher: J.Elect.Materials 4 1143 (1975)CrossRefADSGoogle Scholar
  2. 2.
    N. S. Shiren, W. Arnold and T. G. Kazyaka: Phys.Rev.Letters 39 239 (1977)CrossRefADSGoogle Scholar
  3. 3.
    R. L. Melcher: Phys.Rev.Letters 43 939 (1979)CrossRefADSGoogle Scholar
  4. 4.
    D. J. Meredith, J. A. Pritchard and J. K. Wigmore: Phys.Letts. 86A 376 (1981)CrossRefADSGoogle Scholar
  5. 5.
    J. J. Gagnepain and R. Besson: Physical Acoustics vol.11 ( Academic Press, New York, 1975 ) p. 245Google Scholar
  6. 6.
    R. A. Graham: J.Appl.Phys. 48 2153 (1977)CrossRefADSGoogle Scholar
  7. 7.
    C. Laermans: Phys.Rev.Letters 42 250 (1979)CrossRefADSGoogle Scholar
  8. 8.
    P. K. Grewal and M. J. Lea., P.Phys.O (Solid State) 16 247 (1982)CrossRefADSGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 1984

Authors and Affiliations

  • D. J. Meredith
    • 1
  • H. Mkhwanazi
    • 1
  • J. K. Wigmore
    • 1
  • T. Miyasato
    • 2
  1. 1.Physics DepartmentUniversity of LancasterLancasterEngland
  2. 2.Institute of Scientific and Industrial ResearchUniversity of OsakaSuita, Osaka 565Japan

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