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The Conduction Mechanism of Highly Disordered Semiconductors (A Possible Model for Semiconducting Glasses) II. Influence of Charged Defects
Author(s) -
Böer K. W.
Publication year - 1969
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.19690340236
Subject(s) - saddle point , saddle , condensed matter physics , semiconductor , carrier scattering , scattering , thermal conduction , conduction band , mean free path , band gap , coulomb , conductivity , physics , atomic physics , materials science , chemistry , electron , optics , quantum mechanics , mathematical optimization , geometry , mathematics
The band perturbation due to a high density of charged defects is discussed, and it is shown that the saddle point between Coulomb‐repulsive centers can act as a potential barrier, above which conductivity takes place, if the average distance between these saddle points is small compared to the mean free path of the carriers. For a defect density of 10 20 cm −3 the saddle points lie ≈ 0.25 eV from the respective band edges and are an average of 20 Å apart from each other, while the mean free path, as calculated from ion‐scattering for carriers of an energy 1 kT above these saddle points is about three times as large. These potential barriers are suggested to be responsible for the fact, that for glasses the thermal activation energy for semiconductivity is usually 0.1 to 0.3 eV larger than half the optical band gap.