Near-edge optical absorption behavior of sputter deposited hafnium dioxide

Journal Article · Fri Jun 15 04:00:00 EDT 2007 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.2750406· OSTI ID:20979445

Hoppe, E E; Sorbello, R S; Aita, C R ^[1]

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1. Advanced Coatings Experimental Laboratory, University of Wisconsin-Milwaukee, P.O. Box 784, Milwaukee, Wisconsin 53201 (United States)

The absorption behavior at the onset of the ultraviolet optical edge of sputter deposited hafnium dioxide is reported. X-ray diffraction showed that films grown at room temperature on fused silica were nanocrystalline monoclinic, and that after air annealing at 1273 K for 24 h, they were well-crystallized monoclinic with a strong (11-1) texture. Spectrophotometry was used to measure transmission and reflection in the 190-1100 nm wavelength range. The absorption coefficient, {alpha}(E), as a function of energy, E, was determined from spectrophotometric data. Two persistent features were identified. Feature I is the rapid rise in {alpha}(E) above 6.24 eV that is unchanged upon annealing. A linear {alpha}(E){sup 1/2} vs E dependence associates this feature with indirect interband transitions. Feature II initiates at {approx}5.65 eV and saturates at 5.94 eV. It appears as a low energy shoulder on the absorption edge of the as-grown films and develops into a discrete and more intense band in the annealed films, in which the coordination of Hf with seven O is satisfied. Its annealing behavior explicitly shows that feature II is not caused by an O defect, but is intrinsic to monoclinic HfO{sub 2}.

• OSTI ID: 20979445
• Journal Information: Journal of Applied Physics, Journal Name: Journal of Applied Physics Journal Issue: 12 Vol. 101; ISSN JAPIAU; ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ABSORPTION
ANNEALING
CRYSTAL DEFECTS
DEPOSITION
DIELECTRIC MATERIALS
ENERGY DEPENDENCE
ENERGY-LEVEL TRANSITIONS
EV RANGE 01-10
HAFNIUM OXIDES
MONOCLINIC LATTICES
NANOSTRUCTURES
SILICA
SPECTROPHOTOMETRY
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 1000-4000 K
TEXTURE
TIME DEPENDENCE
ULTRAVIOLET SPECTRA
X-RAY DIFFRACTION