Modulation of Electrical and Thermal Properties of Niobium Oxide by Alternating Oxygen and Hydrogen Plasma in Atomic Layer Deposition

Transition metal oxide films are a key material for various applications, such as neuromorphic devices, electrochemical energy systems, and optical systems. The material characteristics significantly vary with its stoichiometry between metal to oxygen due to its polymorphic nature. Despite much of previous work on conventional transition metal oxide, the impact of oxidation state on both electrical and thermal properties has been left underexplored. In this work, we modulate the stoichiometry of the metal oxide via alternating oxygen and hydrogen plasma during atomic layer deposition. We use niobium oxide as a sample material, demonstrating tunable electrical and thermal properties. Through systematic material characterization and electrical measurements, we find that the dielectric constant of niobium oxide is enhanced with increased electronic polarizability. Using the optical pump-probe method, the thermal properties are found to be tuned with the stoichiometry of niobium oxide.