Transmission electron microscopy analysis of reduction reactions and phase transformations in Nb₂O₅ films deposited by atomic layer deposition

Amorphous films of Nb2O5 composition were deposited by thermal atomic layer deposition on (001) Si substrates and subsequently crystallized annealing in forming gas at temperatures ranging from 550 °C to 1000 °C. After subjecting these an 850 anneal, cross-sectional transmission electron microscopy revealed the presence B-Nb2O5 T-Nb2O5 phases matrix, as well reduced R-NbO2 floret-shaped regions. Annealing completed reduction process, resulting insulator-to-metal transition (IMT) capable T-NbO2 phase throughout film. ALD also electron-transparent SiN membranes then subjected anneals. Here, anneal induced without inducing phase. The retained while phase, but bringing process completion effectiveness reducing treatment induce for substrates, stopping short this membranes, suggests importance SiO2 substrate contributing reaction that results technologically important (IMT)-capable