%0 Journal Article
%A Martil De La Plaza, Ignacio
%A González Díaz, Germán
%A Prado Millán, Álvaro Del
%T Thermally induced changes in the optical properties of SiNx : H films deposited by the electron cyclotron resonance plasma method
%D 1999
%@ 0021-8979
%U https://hdl.handle.net/20.500.14352/59258
%X We analyze the effect of thermal processes on the optical properties (refractive index, optical gap, Tauc coefficient, and Urbach energy) of SiNx:H films. Films with three different nitrogen to silicon ratios (x = 0.97, x = 1.43, and x = 1.55, respectively) were deposited by a chemical vapor deposition technique assisted by an electron cyclotron resonance generated plasma. After deposition they were subjected to rapid thermal annealing at temperatures ranging from 300 degrees C to 1050 degrees C. We found that the percolation threshold for Si-Si bonds (at x = 1.1) separates films with different response to thermal treatments. The changes of the Tauc coefficient and the Urbach energy at moderate annealing temperatures indicate a structural relaxation of the network for the films with x above the percolation threshold, while at higher temperatures the trends are inverted. In the case of x below the percolation limit the inversion point is not observed. These trends are well correlated with the width of the Si-N infrared stretching absorption band. Additionally the samples with as-grown x = 1.43 show a good correlation between the Urbach energy and the density of unpaired spins in silicon dangling bonds. (C) 1999 American Institute of Physics. [S0021-8979(99)08016-0].
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