Electrical characteristics of Ga2O3–TiO2 nanomixed films grown by plasma-enhanced atomic-layer deposition for gate dielectric applications

Nanomixed Ga2O3–TiO2 films with 5 nm thickness were deposited at 200 °C on Si (001) substrates using plasma-enhanced atomic-layer deposition for gate dielectric applications. While TiO2 films deposited on Si substrates are crystallized at an annealing temperature of 500 °C, Ga2O3–TiO2 nanomixed films show an incipient crystallization at 950 °C and exhibited a good thermal stability even at about 950 °C for 1 min. The dielectric constant of TaN∕Ga2O3–TiO2∕Si capacitors is larger than that of TaN∕TiO2–Ga2O3∕Si capacitors in nanomixed films annealed at 900 °C for 1 min. The EOT of the TaN∕Ga2O3–TiO2∕Si capacitors was ∼6Å up to an annealing temperature of 700 °C but increases with increasing annealing temperature above 700 °C for 1 min. The TaN∕Ga2O3–TiO2∕Si capacitors annealed at 1000 °C exhibit a leakage current density of ∼4×10−3A∕cm2 at −1.5V and an interfacial charge density of 1.5×1011cm−2eV−1. The Ga2O3–TiO2 nanomixed films are new candidate materials for gate dielectric applications.