276 research outputs found
Influence of substrate bias on the structural and dielectrical properties of magnetron-sputtered BaxSr1-xTiO3 thin films
The application of a substrate bias during rf magnetron sputtering alters the
crystalline structure, grain morphology, lattice strain and composition of
BaxSr1-xTiO3 thin films. As a result, the dielectric properties of
Pt/BaxSr1-xTiO3/Pt parallel-plate capacitors change significantly. With
increasing substrate bias we observe a clear shift of the ferroelectric to
paraelectric phase transition towards higher temperature, an increase of the
dielectric permittivity and tunability at room temperature, and a deterioration
of the dielectric loss. To a large extent these changes correlate to a gradual
increase of the tensile in-plane film strain with substrate bias and an abrupt
change in film composition.Comment: 24 pages, 8 figures, submitted to Ferroelectric
Coating and functionalization of high density ion track structures by atomic layer deposition
In this study
flexible TiO
2
coated
porous
Kapton
membranes are presented having electron
multiplication properties. 800 nm crossing pores were fabricated into 50
m thick Kapton
membranes using ion track technology and chemical etching. Consecutively,
50 nm TiO
2
films were deposited i
nto
the pores of the
Kapton
membranes
by atomic layer deposition
using Ti(
i
OPr)
4
and water as precursors at 250 °C.
The TiO
2
films and coated membranes
were studied by scanning electro
n microscopy (SEM), X
-
ray diffraction (XRD) and X
-
ray
reflectometry (XRR). Au metal electrod
e fabrication onto both sides of the coated foils was
achieved by electron beam evaporation.
The
electron
multipliers were obtained by joining
3
two coated
membranes
separated by a conductive spacer.
The results show that electron
multiplication can be achie
ved using ALD
-
coated flexible
ion track polymer foils
Structural and Optical Characterization of ZnS Ultrathin Films Prepared by Low-Temperature ALD from Diethylzinc and 1.5-Pentanedithiol after Various Annealing Treatments
The structural and optical evolution of the ZnS thin films prepared by atomic layer deposition (ALD) from the diethylzinc (DEZ) and 1,5-pentanedithiol (PDT) as zinc and sulfur precursors was studied. A deposited ZnS layer (of about 60 nm) is amorphous, with a significant S excess. After annealing, the stoichiometry improved for annealing temperatures ≥400 °C and annealing time ≥2 h, and 1:1 stoichiometry was obtained when annealed at 500 °C for 4 h. ZnS crystallized into small crystallites (1–7 nm) with cubic sphalerite structure, which remained stable under the applied annealing conditions. The size of the crystallites (D) tended to decrease with annealing temperature, in agreement with the EDS data (decreased content of both S and Zn with annealing temperature); the D for samples annealed at 600 °C (for the time ≤2 h) was always the smallest. Both reflectivity and ellipsometric spectra showed characteristics typical for quantum confinement (distinct dips/peaks in UV spectral region). It can thus be concluded that the amorphous ZnS layer obtained at a relatively low temperature (150 °C) from organic S precursor transformed into the layers built of small ZnS nanocrystals of cubic structure after annealing at a temperature range of 300–600 °C under Ar atmosphere
Structural and Optical Characterization of ZnS Ultrathin Films Prepared by Low-Temperature ALD from Diethylzinc and 1.5-Pentanedithiol after Various Annealing Treatments
The structural and optical evolution of the ZnS thin films prepared by atomic layer deposition (ALD) from the diethylzinc (DEZ) and 1,5-pentanedithiol (PDT) as zinc and sulfur precursors was studied. A deposited ZnS layer (of about 60 nm) is amorphous, with a significant S excess. After annealing, the stoichiometry improved for annealing temperatures ≥400 °C and annealing time ≥2 h, and 1:1 stoichiometry was obtained when annealed at 500 °C for 4 h. ZnS crystallized into small crystallites (1–7 nm) with cubic sphalerite structure, which remained stable under the applied annealing conditions. The size of the crystallites (D) tended to decrease with annealing temperature, in agreement with the EDS data (decreased content of both S and Zn with annealing temperature); the D for samples annealed at 600 °C (for the time ≤2 h) was always the smallest. Both reflectivity and ellipsometric spectra showed characteristics typical for quantum confinement (distinct dips/peaks in UV spectral region). It can thus be concluded that the amorphous ZnS layer obtained at a relatively low temperature (150 °C) from organic S precursor transformed into the layers built of small ZnS nanocrystals of cubic structure after annealing at a temperature range of 300–600 °C under Ar atmosphere
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