Dependence of optical properties on composition of silicon carbonitride thin films deposited at low temperature by PECVD

Guilherme Lavareda, Yuri Vygranenko, Ana Amaral, Carlos Nunes de Carvalho, Nuno Pessoa Barradas, Eduardo Alves, Pedro Brogueira

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1 Citation (Scopus)

Abstract

a-SiCN:H thin films were deposited at 150°C by PECVD using silane, methane and ammonia as precursor gases, with a SiH4:H2 dilution of 1:9. RBS and ERDA were used for determining material composition. The concentration of silicon, carbon and nitrogen in the deposited films was correlated with the respective precursor gas concentration and the incorporation yield of each atomic species was determined and related to the molecular bond energies of precursor gases. Chemical bonding type and density determined by FTIR were also related to the chemical composition of the films. Optical transmission was measured to estimate the optical gap (Eop) and refractive index (n) in the transparent region. Stoichiometric a-SiN has the lowest n (1.74) and highest Eop (4.12 eV) while a-Si:H presents the highest n (3.37) and lowest Eop (1.85 eV). A trade-off between the Eop and n is presented to show the applicability of this ternary material in optical devices.

Original languageEnglish
Article number120434
JournalJournal of Non-Crystalline Solids
Volume551
DOIs
Publication statusPublished - 1 Jan 2021

Keywords

  • Chemical composition
  • Hydrogenated amorphous silicon carbonitride
  • Low temperature deposition
  • Optical properties
  • PECVD
  • Transparent thin-films

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