Correlation between crystallization and oxidation process of ScN films exposed to air

Synthesis and study of ScN thin films

“…In addition, combined SXAS study at Sc L-edge, N K-edge and O K-edge reveal that the effect of oxidation is less pronounced for nitrided samples compared to their metal/interstitial counterparts. This is due to formation of strong Sc-N covalent bonds which results in relatively high Gibb's energy for oxide formation (-6.48 eV) of ScN than metallic Sc-Sc bonds in pure Sc (-9.43 eV) at ≈298 K [13]. Furthermore, our Sc K-edge XANES spectra confirms distinct evolution from hexagonal to octahedral symmetry complemented with a clear rise in the valence state for ScN samples consistent with our XRD results.…”

“…Howbeit, nitrogen vacancies (V N ) are known to form a defect energy level at ≈1.26 eV above the valence band maxima at Γ point of the Brillouin zone [21]. In this context, it is to be mentioned here that significance of high T s depositions in supression of defects were found to be conflicting in literature [13,17,22,23], yet have not been highlighted so far.…”

“…Hence for application based perspectives, to modulate the band structure engineering for superior device performances, so far, most of the studies adopted high vacuum (≤10 −8 Torr) depositions to ensure low defect concentrations with atomically smooth epitaxial growth of ScN thin film samples on variety of single crystal substrates (MgO, Al 2 O 3 , GaN, SiC etc.) [13][14][15][16], and few of them aided with process parameters are tabulated in Table I. As can be seen from Table I, conventional use of high substrate temperature (T s ≥ 823 K) has been an integral part during the synthesis of ScN thin film samples, possibly due to higher adatom mobility promoting enhanced crystalline defect free ScN growth [17].…”

“…In terms of defects, even though it is well known that during the growth of ScN itself, finite incorporation of substitutional (O N ) and/or interstitial oxygen (O i ) is inherent regardless of T s [16,18,20], but combined study of first principles density functional theory (DFT) with site occupancy disorder technique reveals that the electronic band structure of ScN remains unaltered despite of a shift of the Fermi energy level to the bottom of the conduction band [4]. Nonetheless, only recently, the primary contribution of oxygen incorporation has also been attributed to the surface oxidation [13,17]. Howbeit, nitrogen vacancies (V N ) are known to form a defect energy level at ≈1.26 eV above the valence band maxima at Γ point of the Brillouin zone [21].…”

Twin domains of ScN (001) films on MgO (001)

“…Scandium nitride (ScN) has attracted a great deal of attention in recent years due to its promising properties as high hardness, temperature stability and high electrical conductivity [1], [2]. Twin domains have been already studied in this interesting material for some other configurations including ScN crystalline and polycrystalline growth on different substrates [3]- [5]. Five epitaxial (001) ScN films from 145 nm to 1080 nm thicknesses were deposited at the same conditions on MgO (001) substrate by DC reactive magnetron sputtering.…”