AlN:Cr thin films synthesized by pulsed laser deposition: Studies by X-ray diffraction and spectroscopic ellipsometry

A. Szekeres, S. Bakalova, S. Grigorescu, A. Cziraki, G. Socol, C. Ristoscu, I. N. Mihailescu

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

The structure and optical properties of AlN thin films doped with Cr atoms were studied by X-ray diffractometry, Fourier transform infrared spectroscopy and spectroscopic ellipsometry analyses. The films were synthesized by pulsed laser deposition from an AlN:Cr (10% Cr) target onto Si(1 0 0) wafers in vacuum at residual pressure of 10 -3 Pa or in nitrogen at a dynamic pressure of 0.1 Pa. The study of the XRD patterns revealed that both phases co-existed in the synthesized films and that the amorphous one was prevalent. Two different amorphous matrices, i.e. two types of chemical bond arrangements, were found in films deposited at 0.1 Pa N 2 . By difference, deposition in vacuum resulted in the coexistence of hexagonal and cubic crystallites embedded into an amorphous matrix. The introduction of Cr atoms into the AlN lattice causes a broadening of the IR spectrum along with the shift toward higher wavenumbers of the characteristic Al-N bands at 2351 cm -1 and 665 cm -1 , respectively. This was related to the generation of a compressive stress inside films. In comparison to the optical constants of pure AlN films, the synthesized AlN:Cr films exhibited a smaller refractive index and showed a weak absorption throughout the 300-800 nm spectral region, characteristic to amorphous AlN structure.

Original languageEnglish
Pages (from-to)5271-5274
Number of pages4
JournalApplied Surface Science
Volume255
Issue number10
DOIs
Publication statusPublished - Mar 1 2009

Keywords

  • Compressive stress in PLD films
  • Cr-doped AlN films
  • Optical characteristics of AlN films
  • Spectroscopic ellipsometry

ASJC Scopus subject areas

  • Chemistry(all)
  • Condensed Matter Physics
  • Physics and Astronomy(all)
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films

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