The authors investigate sputtering of a Ti₃SiC₂ compound target at temperatures ranging from RT (no applied external heating) to 970 °C as well as the influence of the sputtering power at 850 °C for the deposition of Ti₃SiC₂ films on Al₂O₃(0001) substrates. Elemental composition obtained from time-of-flight energy elastic recoil detection analysis shows an excess of carbon in all films, which is explained by differences in the angular distribution between C, Si, and Ti, where C scatters the least during sputtering. The oxygen content is 2.6 at. % in the film deposited at RT and decreases with increasing deposition temperature, showing that higher temperatures favor high purity films. Chemical bonding analysis by x-ray photoelectron spectroscopy shows C–Ti and Si–C bonding in the Ti₃SiC₂ films and Si–Si bonding in the Ti₃SiC₂ compound target. X-ray diffraction reveals that the phases Ti₃SiC₂, Ti₄SiC₃, and Ti₇Si₂C₅ can be deposited from a Ti₃SiC₂ compound target at substrate temperatures above 850 °C and with the growth of TiC and the Nowotny phase Ti₅Si₃C_x at lower temperatures. High-resolution scanning transmission electron microscopy shows epitaxial growth of Ti₃SiC₂, Ti₄SiC₃, and Ti₇Si₂C₅ on TiC at 970 °C. Four-point probe resistivity measurements give values in the range ∼120 to ∼450 μΩ cm and with the lowest values obtained for films containing Ti₃SiC₂, Ti₄SiC₃, and Ti₇Si₂C₅.

The electronic structure and chemical bonding of ß-Ta synthesized as a thin 001-oriented film (space group P 2₁m) is investigated by 4f core level and valence band X-ray photoelectron spectroscopy and compared to α-Ta bulk. For the b-phase, the 4f_7/2 peak is located at 21.91 eV and with the 4f_5/2 at 23.81 eV which is 0.16 eV higher compared to the corresponding 4f peaks of the a-Ta reference. We suggest that this chemical shift originates from higher resistivity and tensile strain in the ß-Ta film. Furthermore, the 5d-5s states at the bottom of the valence band are shifted by 0.75 eV towards higher binding energy in ß-Ta compared to α-Ta. This is a consequence of the lower number of nearest neighbors with four in ß-Ta compared to eight in the α-Ta phase. The difference in the electronic structures, spectral line shapes of the valence band and the energy positions of the Ta 4f, 5p core-levels of b-Ta versus a-Ta are discussed in relation to calculated states of ß-Ta and α-Ta. In particular, the lower number of states at the Fermi level of ß-Ta (0.557 states/eV/atom) versus α-Ta (1.032 states/eV/atom) that according to Mott’s law should decrease the conductivity in metals and affect the stability by charge redistribution in the valence band. This is experimentally supported from resistivity measurements of the film yielding a value of ~170 µW cm in comparison to α-Ta bulk with a reported value of ~13.1 µW cm.

W-B-C films were deposited on Si(100) substrates held at elevated temperature by reactive sputtering from a W target in Kr/trimethylboron (TMB) plasmas. Quantitative analysis by Xray photoelectron spectroscopy (XPS) shows that the films are W-rich between ~ 73 and ~ 93 at.% W. The highest metal content is detected in the film deposited with 1 sccm TMB. The C and B concentrations increase with increasing TMB flow to a maximum of ~18 and ~7 at.%, respectively, while the O content remains nearly constant at 2-3 at.%. Chemical bonding structure analysis performed after samples sputter-cleaning reveals C-W and B-W bonding and no detectable W-O bonds. During film growth with 5 sccm TMB and 500 o C or with 10 sccm TMB and 300-600 o C thin film X-ray diffraction shows the formation of cubic 100-oriented WC1-x with a possible solid solution of B. Lower flows and lower growth temperatures favor growth of W and W2C, respectively. Depositions at 700 and 800 o C result in the formation of WSi2 due to a reaction with the substrate. At 900 o C, XPS analysis shows ~96 at.% Si in the film due to Si interdiffusion. Scanning electron microscopy images reveal a fine-grained microstructure for the deposited WC1-x films. Nanoindentation gives hardness values in the range from ~23 to ~31 GPa and reduced elastic moduli between ~220 and 280 GPa in the films deposited at temperatures lower than 600 o C. At higher growth temperatures the hardness decreases by a factor of 3 to 4 following the formation of WSi2 at 700-800 o C and Si-rich surface at 900 o C.

The variation in local atomic structure and chemical bonding of ZrH_x (x=0.15, 0.30, 1.16) magnetron sputtered thin films are investigated by Zr K-edge (1s) X-ray absorption near-edge structure and extended X-ray absorption fine structure spectroscopies. A chemical shift of the Zr K-edge towards higher energy with increasing hydrogen content is observed due to charge-transfer and an ionic or polar covalent bonding component between the Zr 4d and the H 1s states with increasing valency for Zr. We find an increase in the Zr-Zr bond distance with increasing hydrogen content from 3.160 Å in the hexagonal closest-packed metal (a-phase) to 3.395 Å in the understoichiometric d-ZrH_x film (CaF₂-type structure) with x=1.16 that largely resembles that of bulk d-ZrH₂. For yet lower hydrogen contents, the structures are mixed a- and d-phases, while sufficient hydrogen loading (x>1) yields a pure δ-phase that is understoichiometric, but thermodynamically stable. The change in the hydrogen content and strain is discussed in relation to the corresponding change of bond lengths, hybridizations, and trends in electrical resistivity.

The influence of B4C incorporation during magnetron sputter deposition of Cr/Sc multilayers intended for soft X-ray reflective optics is investigated. Chemical analysis suggests formation of metal: boride and carbide bonds which stabilize an amorphous layer structure, resulting in smoother interfaces and an increased reflectivity. A near-normal incidence reflectivity of 11.7%, corresponding to a 67% increase, is achieved at λ = 3.11 nm upon adding 23 at.% (B + C). The advantage is significant for the multilayer periods larger than 1.8 nm, where amorphization results in smaller interface widths, for example, giving 36% reflectance and 99.89% degree of polarization near Brewster angle for a multilayer polarizer. The modulated ion-energy-assistance during the growth is considered vital to avoid intermixing during the interface formation even when B + C are added.

We investigate the trends in mixing thermodynamics of Cr_1-xSc_xN solid solutions in the cubic B1 structure and their electronic density of state by first-principle calculations, and thin-film synthesis of Cr_1-xSc_xN solid solutions by reactive dc magnetron sputtering. Films with the composition Cr_0.92Sc_0.08N exhibit a thermoelectric power factor of about 8x10^-4 Wm^-1K^-2at 770 K, similar to CrN. The results show that the disordered Cr_1-xSc_xN solid solutions is thermodynamically stable in B1 solid solutions at T = 800°C rather than in the B1- L11 ordered solid solutions stable at 0 K. The calculated electronic density of state (DOS) indicates a positive bowing parameter for the electronic band gap of Cr1-xScxN solid solutions. The calculated DOS suggest possible improvement of power factor due to Sc 3d orbital delocalization on Cr 3d orbital gives decreasing electrical resistivity with retained Seebeck coefficient in Cr-rich regime, consistent with the experimentally observed high power factor for the solid solution.

Zirconium diboride (ZrB₂) exhibits high hardness and high melting point, which is beneficial for applications in for e.g. metal cutting. However, there is limited data on the mechanical properties of ZrB₂ films and no data on epitaxial films. In this study, ZrB₂(0001) thin films, with thicknesses up to 1.2 μm, have been deposited on Al₂O₃(0001) substrates by direct current magnetron sputtering from a compound target. X-ray diffraction and transmission electron microscopy show that the films grow epitaxially with two domain types exhibiting different in-plane epitaxial relationships to the substrate. The out-of-plane epitaxial relationship was determined to ZrB₂(0001)|Al₂O₃(0001) and the in-plane relationships of the two domains to ZrB₂[100]‖Al₂O₃[100] and ZrB₂[110]‖Al₂O₃[100]. Mechanical properties of the films, evaluated by nanoindentation, showed that all films exhibit hardness values above 45 GPa, a reduced Young's modulus in the range 350–400 GPa, and a high elastic recovery of 70% at an applied load of 9000 μN.

Multilayered thin films of Al/Cu/Fe have been prepared by magnetron sputtering and annealed into the quasicrystalline or approximant phases, for Al₂O₃ or Si substrates, respectively. The nanomechanical and nanotribological properties; hardness, elastic modulus, friction and toughness, have been measured using a triboindenter and analytical methods. The approximant phase, annealed at 600 °C for 4 h, proved to be harder and had higher elastic modulus values than the quasicrystalline phase, about, 15.6 GPa and 258 GPa, respectively. The fracture toughness of the approximant, <0.1 MPa/m^½, was however inferior to that of the quasicrystals with 1.5 MPa/m^½. The friction coefficients were measured in a range of 0.10-0.14 for the quasicrystalline and approximant thin films.

(Ti_0.25B_0.75)_1−xSi_xN_y, 0≤x≤0.89, 0.9≤y≤1.25, thin films were reactively grown on Si(001) substrates by dc magnetron sputtering from compound TiB2 and elemental Si targets. The films can be grown in a fully electron-diffraction amorphous state with x>0.46, as evidenced by XRD and HR-TEM investigations. With x=0, BN form onion-like sheets surrounding TiNnanograins. Substrate temperatures, Ts=100-600 ◦C, has a minor effect of the film structure and properties, due to limited surface diffusion.

Ion-assisted growth with substrate bias voltages, Vb, between -50 V and -200 V, favors densification of amorphous structures over nanocrystalline formation, and improves mechanical properties. A maximum hardness value of 26.8±0.7 GPa is found for an amorphous (Ti_0.25B_0.75)_0.39Si_0.61N_1.15 film grown with substrate temperature T_s=400 °C and substrate bias voltage V_b=-100 V.

Reactive sputtering by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a Zr target in Ar/H-2 plasmas was employed to deposit Zr-H films on Si(100) substrates, and with H content up to 61 at.% and O contents typically below 0.2 at.% as determined by elastic recoil detection analysis. X-ray photoelectron spectroscopy reveals a chemical shift of similar to 0.7 eV to higher binding energies for the Zr-H films compared to pure Zr films, consistent with a charge transfer from Zr to H in a zirconium hydride. X-ray diffraction shows that the films are single-phase delta-ZrH2 (CaF2 type structure) at H content greater thansimilar to 55 at.% and pole figure measurements give a 111 preferred orientation for these films. Scanning electron microscopy cross-section images show a glasslike microstructure for the HiPIMS films, while the DCMS films are columnar. Nanoindentation yield hardness values of 5.5-7 GPa for the delta-ZrH2 films that is slightly harder than the similar to 5 GPa determined for Zr films and with coefficients of friction in the range of 0.12-0.18 to compare with the range of 0.4-0.6 obtained for Zr films. Wear resistance testing show that phase-pure delta-ZrH2 films deposited by HiPIMS exhibit up to 50 times lower wear rate compared to those containing a secondary Zr phase. Four-point probe measurements give resistivity values in the range of similar to 100-120 mu Omega cm for the delta-ZrH2 films, which is slightly higher compared to Zr films with values in the range 70-80 mu Omega cm.