Axel Flink

Growth and characterization of TiN/SiN(001) superlattice films

We report the layer structure and composition in recently discovered TiN/SiN(001) superlattices deposited by dual-reactive magnetron sputtering on MgO(001) substrates. High-resolution transmission ...

Deposition of single-crystal Ti2AlN thin films by reactive magnetron sputtering from a 2Ti:Al compound target

Single-crystal Ti2AlN (0001) thin films were grown on (111) oriented MgO substrates kept at 830°C by ultrahigh vacuum dc reactive magnetron sputtering from a compound 2Ti:Al target in a mixed Ar∕N2 discharge. The effects of variations in the nitrogen partial pressure on the phase composition of the films were studied. Results from transmission electron microscopy, x-ray diffraction, and elastic recoil detection analysis show a narrow region for growth of Ti2AlN MAX phase with respect to the nitrogen content in the discharge. Perovskite Ti3AlN and intermetallic Ti3Al and TiAl phases dominate at nitrogen depletion. For overstoichiometric deposition conditions with respect to Ti2AlN, a phase mixture with NaCl-structured TiN is obtained. Epitaxial growth is observed with a layer-by-layer mode on the 0001 basal planes for all phases. A superstructure in the TiN phase is also observed along [111] with the repetition distance of 7.34A, most likely related to Al segregation. Nanoindentation shows that the film ha...

Role of carbon in boron suboxide thin films

Boron suboxide thin films, with controlled carbon content, were grown by rf dual magnetron sputtering of boron and carbon targets in an argon–oxygen atmosphere. Film composition, structure, mechanical, and electrical properties were evaluated with x-ray photoelectron spectroscopy, Auger electron spectroscopy, x-ray diffraction, transmission electron microscopy, nanoindentation, and high-frequency capacitance–voltage measurements. X-ray amorphous B–O–C films (O/B=0.02) showed an increase in density from 2.0 to 2.4 g/cm3 as C content was increased from 0 to 0.6 at. % and the film with the highest density had nanocrystalline inclusions. The density increase occurred most likely due to the formation of B–C bonds, which are shorter than B–B bonds. All measured material properties were found to depend strongly on the C content and thus film density. The elastic modulus increased from 188 to 281 GPa with the increasing C content, while the relative dielectric constant decreased from 19.2 to 0.9. Hence, B–O–C fil...

Structure and electrical properties of Nb-Ge-C nanocomposite coatings

Nb-Ge-C nanocomposite thin films were deposited by dc magnetron sputtering using three elemental targets. The films consist of substoichiometric NbCx in a nanometer-thick matrix of amorphous C and Ge. Films with no Ge contain grains that are elongated in the growth direction with a (111) preferred crystallographic orientation. With the addition of ∼12 at. % Ge, the grains are more equiaxed and exhibit a more random orientation. At even higher Ge contents, the structure also becomes denser. The porous structure of the low Ge content films result in O uptake from the ambient. With higher C content in the films both the amount of amorphous C and C/Nb-ratio increases. The contact resistance was measured by four-point technique as a function of contact force between 0 and 10 N. The lowest contact resistance (1.7 mΩ) is obtained at 10 N. The resistivity varies between 470 and 1700 μΩ·cm depending on porosity and O content.