Magnitude of the electric dipole moment in semiconductors

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SUMMARY

The discussion focuses on the calculation of the electric dipole moment in semiconductors using k.p theory, particularly for band-to-band transitions. It highlights a discrepancy where the calculated dipole moment exceeds the dimensions of the elementary unit cell, raising questions about the validity of the overlap integral between Bloch functions and the position operator. Additionally, it critiques the common reliance on the vector potential and electron momentum (A.p) in textbooks, noting a lack of references that utilize the electric dipole moment throughout the entire calculation process.

PREREQUISITES
  • Understanding of k.p theory in semiconductor physics
  • Familiarity with Bloch functions and their properties
  • Knowledge of electric dipole moments and their significance in optical processes
  • Basic concepts of band-to-band transitions in semiconductors
NEXT STEPS
  • Research the application of k.p theory in semiconductor band structure calculations
  • Explore the mathematical formulation of overlap integrals in solid-state physics
  • Investigate the role of electric dipole moments in optical transitions
  • Find comprehensive references that utilize electric dipole moments in semiconductor calculations
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Physicists, semiconductor researchers, and students studying solid-state physics who are interested in the theoretical aspects of electric dipole moments and their applications in semiconductor optics.

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When using k.p theory to calculate the magnitude of the electric dipole moment in semiconductors for band-to-band transitions, the value of the dipole moment is basically fitted to the effective mass of the electron in the conduction band. However, the values turn out to be larger than the dimension of the elementary unit cell, which does not make that much sense. We are basically calculating an overlap integral between two Bloch functions which have unit cell dimensions and a position operator. How can that ever be larger than the unit cell?
 
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As a follow up to the previous question. While deriving optical processes in semiconductors practically all textbooks use the vector potential and the electron momentum (A.p). I haven;t found a single reference that actually uses the electric dipole moment to do this and yet this is the value all books state at the end of the calculation. Does anybody have a solid reference that simply uses the electric dipole moment from the beginning to the end of the calculation?
 

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