Strain-related structural and vibrational properties of thin epitaxial AIN layers

V. Darakchieva, J. Birch, M. Schubert, T. Paskova, S. Tungasmita, G. Wagner, A. Kasic, B. Monemar

Research output: Contribution to journalArticle

51 Citations (Scopus)

Abstract

The effect of film thickness on the strain and structural properties of thin epitaxial AIN films has been investigated by high resolution x-ray diffraction techniques and transmission electron microscopy. As a result a sublayer model of the degree of strain and related defects for all films is proposed. A sublayer with low defect density and a strain gradient is found to be present in all films and it reaches a maximum thickness of 65 nm. The films are compressively strained and the strain relaxation after a thickness of 65 nm is shown to be accompanied by misfit dislocation generation and increase of the mosaic tilt. The vibrational properties of the films have been studied by generalized infrared spectroscopic ellipsometry. The proposed sublayer model has been successfully applied to the analysis of the ellipsometry data through model calculations of the infrared dielectric function which confirm the sublayer model. It is found that the strain gradient results in a gradient of the phonon mode frequencies and broadening parameter. The initial strain relaxation in the films leads to narrowing of the observable infrared modes, while further strain relaxation broadens the modes when substantial defect generation occurs.

Original languageEnglish (US)
Article number045411
Pages (from-to)045411-1-045411-10
JournalPhysical Review B - Condensed Matter and Materials Physics
Volume70
Issue number4
DOIs
StatePublished - Jul 1 2004

Fingerprint

structural strain
Epitaxial layers
Strain relaxation
Infrared radiation
gradients
ellipsometry
defects
Defects
Spectroscopic ellipsometry
Defect density
Epitaxial films
Ellipsometry
Dislocations (crystals)
Film thickness
Structural properties
Diffraction
Transmission electron microscopy
x ray diffraction
film thickness
X rays

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Darakchieva, V., Birch, J., Schubert, M., Paskova, T., Tungasmita, S., Wagner, G., ... Monemar, B. (2004). Strain-related structural and vibrational properties of thin epitaxial AIN layers. Physical Review B - Condensed Matter and Materials Physics, 70(4), 045411-1-045411-10. [045411]. https://doi.org/10.1103/PhysRevB.70.045411

Strain-related structural and vibrational properties of thin epitaxial AIN layers. / Darakchieva, V.; Birch, J.; Schubert, M.; Paskova, T.; Tungasmita, S.; Wagner, G.; Kasic, A.; Monemar, B.

In: Physical Review B - Condensed Matter and Materials Physics, Vol. 70, No. 4, 045411, 01.07.2004, p. 045411-1-045411-10.

Research output: Contribution to journalArticle

Darakchieva, V, Birch, J, Schubert, M, Paskova, T, Tungasmita, S, Wagner, G, Kasic, A & Monemar, B 2004, 'Strain-related structural and vibrational properties of thin epitaxial AIN layers', Physical Review B - Condensed Matter and Materials Physics, vol. 70, no. 4, 045411, pp. 045411-1-045411-10. https://doi.org/10.1103/PhysRevB.70.045411
Darakchieva, V. ; Birch, J. ; Schubert, M. ; Paskova, T. ; Tungasmita, S. ; Wagner, G. ; Kasic, A. ; Monemar, B. / Strain-related structural and vibrational properties of thin epitaxial AIN layers. In: Physical Review B - Condensed Matter and Materials Physics. 2004 ; Vol. 70, No. 4. pp. 045411-1-045411-10.
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