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Title: Electrical characteristics of amorphous silicon Schottky barriers
Author: Archibald, I. W.
ISNI:       0000 0001 3426 5224
Awarding Body: Durham University
Current Institution: Durham University
Date of Award: 1984
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The behaviour of the admittance of an a-Si Schottky barrier as a function of bias, small signal measuring frequency and temperature is not well understood. In this thesis model calculations are described which are both well defined and comprehensive in their description of the Schottky barrier admittance. These calculations allow a better understanding of experimental admittance plots. Various methods are developed for finding, from Schottky barrier admittance measurements, the density of states in the a-Si mobility gap. The methods are essentially developments of the model admittance calculations, and it should be stressed that the reliability of the deduced density of states depends on the correctness of the initial model premises. In particular it is assumed that the gap state capture cross-sections are all equal and independent of energy. Experimental admittance measurements are presented for an n-type doped a-Si Schottky barrier. The measurements are quite consistent with the developed theory and an estimate of the density of states in the upper half of the mobility gap is calculated. The average value is ~ 10(^17) cm(^-3)eV(^-1) and there is a minimum situated approximately at 0.3 eV below the conduction band mobility edge. This result is in approximate agreement with the density of states deduced by the DLTS technique. It is also deduced from current-voltage measurements that, of the existing theories, Diffusion Theory probably best describes the leakage current in a-Si Schottky barriers. This deduction is arrived at using some novel analysis.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Solid-state physics