Relationship between the physical and structural properties of NbzSiyNx thin films deposited by dc reactive magnetron sputtering

Abstract

Well-isolated L10 FePt-SiN x -C nanocomposite films with large coercivity and small grain size Ionized magnetron sputter deposition of hard nanocomposite TiN/amorphous-silicon nitride filmsThe optical and electrical properties of Nb z Si y N x thin films deposited by dc reactive magnetron sputtering have been investigated as a function of the Si content ͑C Si ͒. Optical properties were studied by both specular reflectivity and spectroscopic ellipsometry. Electrical resistivity was measured by the van der Pauw method at room temperature and as a function of the temperature down to 10 K. Both the optical and electrical properties of Nb z Si y N x films are closely related with the chemical composition and microstructure evolution caused by Si addition. For C Si up to 4 at. % the Si atoms are soluble in the lattice of the NbN crystallites. In this compositional regime, the optical and electrical properties show little dependence on the Si content. Between 4 and 7 at. % the surplus of Si atoms segregates at the grain boundaries, builds an insulating SiN x layer, and originates important modifications in the optical and electrical properties of these films. Further increase of C Si leads to the formation of nanocomposite structures. The electrical properties of these films are well described by the grain-boundary scattering model with low probability for electrons to cross the grain boundary. The appearance of the intragranular-insulating SiN x layer and the reduction of the grain size are noticed in the dielectric function mainly as a strong damping of the plasma oscillation.

A new visible photoluminescence in the conducting Ta–Si–N nanocomposite thin films

“…Also, the electron-tunneling phenomena are temperature dependent. Higher temperature with larger tunneling probability results in lower resistivity for negative temperature coefficient of resistance (TCR) which is a nonmetallic behavior and found in other sputtered transition metal nitrides [25,27,28]. The conducting Ta-Si-N films also exhibit the negative TCR behavior, which increases with FN 2 % and is around À150 to À3000 ppm/1C.…”

“…The calculated grain sizes have been widely used for the symmetrical peaks of nanocomposite Me-Si-N [21,23,25] and they exhibit the acceptable values compared to different measurement methods [21,23,26]. The calculated mean grain sizes of (Ta x ,Si y )N nanocrystals in the Ta 1.7-3.5 nm while the grains in polycrystalline film at 20% are around 15.5 nm.…”

“…The electron mobility is related to the electronic scattering and tunneling at grain (/phase) boundary (GB), grain size (D), inner-crystalline mean free path (L) as well as GB tunneling probability (G) of electrons. According to the grain boundary scattering model [25,27,28] (valid in the limit of L/D41), especially for a nanocomposite amorphous material with tiny D which is significantly smaller than L [25,27], the dc electrical resistivity (r) can be expressed by the equation r ¼ K/(LG L/D ), where K is material-dependent constant related to the effective mass, Fermi velocity and density of carriers. The LG L/D can be represented by an effective mean free path (L G ), L G ¼ LG L/D to describe the electron scattering including the grain-size effect.…”

“…The average size of grains in the direction perpendicular to the reflecting planes [24] of the randomly polycrystalline or nanocomposite amorphous phases can be calculated from the Scherrer's Formula (t ¼ 0:9l=B cos y b , where B represents FWHM in radian, y b is 2y of the peak in degrees and l the wavelength of X-ray in Angstrom or nm) [23][24][25]. The calculated grain sizes have been widely used for the symmetrical peaks of nanocomposite Me-Si-N [21,23,25] and they exhibit the acceptable values compared to different measurement methods [21,23,26].…”

Structure and physicomechanical properties of NbN-based protective nanocomposite coatings: A review

“…These structures obey two basic mechanisms of formation of a high coating hardness-the formation of a hard alloy of Si atoms in the Me-N lattice or the formation of an nc-Me-N nanocomposite and an amorphous phase comprising silicon atoms. Internal stresses do not have a substantial effect on hardness [100].…”