Fabrication and Characterization of High-Quality Epitaxial Nanocolumnar Niobium Films with Abrupt Interfaces on YSZ(001)

Abstract

Niobium (Nb) is a promising refractory metal with a wide variety of technological applications in nanoelectronics, optoelectronics, photonics, and energy-related technologies. However, to further advance the field of nanoelectronics and nanophotonics, very high-quality Nb films with excellent structural order are needed. While much progress has been made in understanding the heteroepitaxy of Nb on oxide substrates, the underlying fundamental mechanisms, especially to realize films showing abrupt interfaces with the substrate and without needing the expensive equipment and/or processing under extreme conditions, remain a challenge. In this context, herein, we demonstrate an approach to stabilize the epitaxial, nanocolumnar bcc Nb films with highly ordered and abrupt interfaces on YSZ(001) substrates using simple and industrially widely adopted sputter deposition. 90 nm Nb films deposited onto YSZ(001) at 500 °C exhibit a strained, epitaxial structure. As evidenced in X-ray diffraction and transmission electron microscopy analyses, the structural quality of Nb films is driven by substrate-assisted selective nanocrystallization. Coupled with granular morphology and high structural quality, the optical properties measured by spectroscopic ellipsometry and reflectivity indicate highly reflective Nb films with enhanced optical constants. Corroborated with surface/interface quality, microstructure, and optical properties, the epitaxial Nb films exhibit excellent mechanical characteristics. The hardness and elastic modulus of the Nb epitaxial films were 18 and 240 GPa, respectively, which are attributed primarily to the growth of a compact nanocolumnar Nb epitaxial film on YSZ.

Study of NiO-NiMn2O4-Patterned Surfaces Fabricated by a Vapor–Solid Process

“…As an example, the diffraction peak corresponding to the (311) planes of NiMn 2 O 4 suffers a shift of around 0.1°to higher angles (Figure 3b) for the samples treated at a higher temperature. This shift could suggest a possible contraction of Actually, microstrain and phase segregation are commonly considered in oxide-based systems fabricated by physical methods at variable temperatures and growth conditions, 27 as that occurred in this case. Rietveld refinements were performed to obtain a deeper understanding of the XRD results.…”

“…This shift could suggest a possible contraction of the crystalline lattice of NiMn 2 O 4 as the temperature used during the thermal treatments increases, although the variable presence of defects or stress should be considered as well. Actually, microstrain and phase segregation are commonly considered in oxide-based systems fabricated by physical methods at variable temperatures and growth conditions, as that occurred in this case.…”

Unexpected Superparamagnetic Behavior in Nanocrystalline Niobium-Based High-Entropy Alloys

“…A trace amount of the Nb–Cr–Ta–V–W RHEA nanoparticle powder was placed on a zero-diffraction plate to eliminate any diffraction peak from the sample stage. The diffraction data were analyzed with HighScore Plus software to extract crystallographic information of RHEA nanoparticles. − …”

Role of Interfacial Morphology in Cu2O/TiO2 and Band Bending: Insights from Density Functional Theory

“…In evaluating the band bending at interfaces, the morphology of materials can influence their interfacial band structure and band bending properties. , With advancements in novel growth techniques, such as molecular-beam epitaxy, epitaxial interfaces of exceptional quality can be fabricated . This is achievable not just between lattice-matched semiconductors but also between materials with considerable differences in their lattice constants .…”

“… 9 , 10 With advancements in novel growth techniques, such as molecular-beam epitaxy, epitaxial interfaces of exceptional quality can be fabricated. 11 This is achievable not just between lattice-matched semiconductors but also between materials with considerable differences in their lattice constants. 12 When these lattice mismatches are present, uniform lattice strain can accommodate them if the layers are sufficiently thin.…”