Changes in the electric resistivity of CrN subsequent to oxygen dissolution

Abstract

Single-phase epitaxial chromium oxynitride thin films containing 11 to 45 mol % oxygen were successfully synthesized on MgO(100) substrates by pulsed laser deposition at 773 K while controlling the ambient oxygen partial pressure. The film compositions were subsequently analyzed by Rutherford backscattering spectroscopy and electron energy-loss spectroscopy, while crystal phases were identified by X-ray diffractometry using the Bragg–Brentano and glancing incidence configurations and by in-plane φ scanning. The microstructures were observed by transmission electron microscopy. The electrical resistance of the films was determined by either the two- or four-probe method. The Cr(N,O) thin film having 11 mol % oxygen exhibited a metallic temperature dependence. In contrast, the films containing oxygen of 13 mol % or higher showed a semiconducting (or insulating) temperature dependence. This resistivity change is believed to result from enhanced electron correlation brought about by increases in oxygen content, sufficient to transform the Cr(N,O) thin film into a Mott insulator.

Strain‐Mediated High Conductivity in Ultrathin Antiferromagnetic Metallic Nitrides

“…Recent works demonstrate that the substitutional replacement of N with O atoms at the CrN surface may act as n ‐type dopants that yield localized states near the conduction band, leading to an enhanced conductivity. [ 35,36 ] T N is 253 K for a 500‐u.c.‐thick CrN film and T N drastically reduces on decreasing the film thickness (Figure 2b). We find that T N shows a finite‐size scaling relation, which is proportional to the B ( t ) λ , where the extrapolated B = 14 ± 0.5 and the shift exponent for the finite‐size scaling factor λ = 0.46 ± 0.05, in consistent with the previous reports.…”

“…We hypothesis that such anomaly in the density may attribute to the small amount of nitrogen-to-oxygen substitutions in the CrN surface with a thickness of a few unit cells. [35,36] This reaction is unavoidable without capping layer at ambient conditions. It is very challenge to quantify the quantity of O content at the CrN surface layers because of the O2 contamination when exposes in air.…”

Structural and electrical properties of (Cr1−x ,V x )N thin films epitaxially grown on MgO(001) substrates

“…11) Nagasawa et al suggested that the semiconducting temperature dependence might be explained by the formation of a Cr-N-O ternary solid solution as a result of residual oxygen in the deposition environment. 27) On the other hand, trace amounts of oxygen in the thin films have been reported to provide conductivity. 28) Our results suggest that the oxygen in CrN may have brought metallic conductivity.…”

Effect of ytterbium on hardness and color of titanium nitride thin films

“…(Ti 1−x Yb x )N thin films were prepared by the pulsed laser deposition (PLD) method on Si(100) substrates. 18,19,29,30) A compound target with a Ti plate (99.9% purity) attached to a Yb disk was used, and the distance between the target and substrate (D TS ) was 60 mm. The substrate temperature T sub was increased to 400 °C, and the pressure in the deposition chamber was reduced to 1 × 10 −6 Pa or less.…”