Work

Temperature-dependent electrical and ferroelectric behavior in magnetron sputtered AlScN thin-film capacitors

Year: 2026

Type: article

Abstract: Al 1–x Sc x N (AlScN) thin films, deposited by magnetron sputtering onto Pt (111)/Si substrates, were investigated to correlate microstructure, surface chemistry, and electrical behavior. Structural characterization confirmed the formation of the wurtzite AlScN phase, while X-ray photoelectron spectroscopy revealed that the surface stoichiometry deviates from the bulk composition due to pronounced oxidation dominated by Sc–O bonding, accompanied by minor Al–O formation and traces of molecular N 2 . Surface oxidation, together with polarization-bound leakage currents and electrode-interface asymmetry, contributes to the asymmetric currents observed during ferroelectric hysteresis measurements. Dielectric spectroscopy shows that extrinsic surface species strongly influence the dielectric response. In the 380 K−400 K range, the material recovers a stable insulating state under low-field excitation, indicating that the elevated dielectric losses observed at intermediate temperatures are extrinsic and do not originate from intrinsic lattice degradation, as verified by heating-cooling cycling. However, electrical recovery remains incomplete, as at 400 K the bulk conductivity returns only to its temperature-independent residual level, pointing to persistent volume conduction. The residual conductivity is associated with intrinsic structural defects that enable charge transport via localised states, consistent with a correlated barrier-hopping conduction mechanism. The coexistence of reversible surface-related effects and intrinsic bulk disorder ultimately defines the electrical limitations of the AlScN heterostructure and provides a consistent explanation for the premature dielectric breakdown observed under high electric fields.

Source: Journal of Alloys and Compounds

DOI: 10.1016/j.jallcom.2026.191116