Abstract
Amorphous tantalum oxide thin films were deposited by reactive r.f. magnetron sputtering onto silicon[001] substrates. Growth temperature, oxygen partial pressure and total gas pressure have been varied for optimizing thin film density. The as-deposited films were annealed in atmosphere at 700°C and transformed into a polycrystalline state. The thin films were analyzed by glancing-angle-of-incidence X-ray diffraction, and variable angle-of-incidence spectroscopic ellipsometry in the near infrared (NIR) to vacuum-ultra-violet (VUV) spectral region for photon energies from 1 to 8.5 eV, and in the infrared (IR) region from 0.03 to 1 eV. We present the IR dielectric functions of amorphous and polycrystalline tantalum oxide, which were obtained by analyzing the experimental ellipsometric data with Lorentzian lineshapes for each phonon resonance absorption. We observe a shift of the characteristic phonon absorption in tantalum oxide to lower frequencies upon sample annealing. The optical properties in the NIR to VUV were analyzed by using a parametric model approach. The dielectric functions obtained thereby were further locally fitted by Lorentzian lineshapes in order to analyze critical point structures due to electronic band-to-band transitions.
Original language | English (US) |
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Pages (from-to) | 283-289 |
Number of pages | 7 |
Journal | Thin Solid Films |
Volume | 388 |
Issue number | 1-2 |
DOIs | |
State | Published - Jun 1 2001 |
Keywords
- Amorphization
- Crystallization
- Infrared spectroscopy
- Optical properties
- Tantalum
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry