Fabrication of High-Quality Co2FeSi/SiOxNy/Si(100) Tunnel Contacts Using Radical-Oxynitridation-Formed SiOxNy Barrier for Si-Based Spin Transistors

A high-quality Co₂FeSi (CFS)/SiO _x N _y /Si tunnel junction was fabricated, in which the SiO _x N _y barrier layer was formed by radical oxynitridation of an Si(100) substrate and the CFS electrode was formed by silicidation of an Fe/Co/amorphous-Si multilayer deposited on the barrier layer. The ultrathin SiO _x N _y barrier layer completely blocked diffusion of Co and Fe atoms into the Si substrate during rapid thermal annealing (RTA) for the silicidation. X-ray diffraction investigations clarified that the CFS film on the ultrathin SiO _x N _y barrier layer exhibited a highly (110)-oriented texture structure and that the film had the L2₁ structure with a high degree of L2₁ order. High resolution cross-sectional transmission electron microscopy investigations revealed that the CFS/SiO _x N _y interface was atomically flat and that the crystal lattice of the CFS film was directly grown on the SiO _x N _y surface without degradation of the crystallinity at the interface.     

Polymer-derived ceramics for electrocatalytic energy conversion reactions

Polymer-derived ceramics (PDCs) are being actively explored in various fields today because of their unique physiochemical properties. Very recent advances in the use of PDCs in energy storage technologies (e.g., batteries, supercapacitors) have motivated researchers to explore the possibilities of PDCs as electrocatalysts for use in energy conversion reactions. Impressively, the tunable functional properties, especially the electrical properties, of PDCs have helped to break through this “bottleneck” and enabled them to become promising materials for use in electrocatalytic conversion. This review presents an in-time summary of the progress in the development of PDCs for electrochemical energy conversion. First, a general introduction to the preparation of PDCs is provided. Later, the factors (e.g., chemical stability, electron conductivity) most closely related to electrocatalytic performance are discussed. Specifically, the parameters that affect the electron conductivity of PDCs are enumerated to delve into advanced strategies for achieving effective electrocatalysts. The relevant electrocatalytic conversion reactions (e.g., hydrogen evolution reaction, oxygen evolution reaction, and oxygen reduction reaction) and utilization of PDCs in these reactions are also comprehensively introduced. Finally, the current challenges and future opportunities for PDC materials in the field of electrochemical energy conversion are summarized.