Optical absorption in amorphous hydrogenated silicon nitride thin films deposited by the electron cyclotron resonance plasma method and subjected to rapid thermal annealing

  • F. L. Martínez /
  • I. Mártil /
  • G. González-Díaz /
  • A. M. Bernal-Oliva /
  • J. M. González-Leal /
  • E. Márquez
Journal ar
Thin Solid Films
  • Volumen: 343-344
  • Número: 1-2
  • Fecha: 01 December 1999
  • Páginas: 433-436
  • ISSN: 00406090
  • Source Type: Journal
  • Document Type: Article
We have analyzed the influence of rapid thermal annealing (from 300 to 1050°C) on the optical properties of a-SiNx:H. Three compositions were investigated: x = 0.97, x = 1.43 and x = 1.55, Two different behaviors are observed depending on whether the as-grown nitrogen to silicon ratio of the samples is above or below the percolation threshold (x = 1.1) of Si-Si bonds, in the matrix of silicon nitride. The samples with x = 1.43 and 1.55 experience an increase of the Tauc coefficient (B) and a decrease of the Urbach parameter (E0) at low annealing temperatures, while at high temperatures the trend is inverted. On the contrary, the samples with x = 0.97 show a slight and continuous increase of B and a similar decrease of E0. The different behavior of the films with x < 1.1 is explained by the percolation of the Si-Si bonds, which maintains the order of the structure at high annealing temperatures, preventing the inversion of the trends of B and E0. © 1999 Elsevier Science S.A. All rights reserved.

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