Electrical characteristics of Ga_2O_3-TiO_2 nanomixed films grown by plasma-enhanced atomic-layer deposition for gate dielectric applications

摘要

Nanomixed Ga_2O_3-TiO_2 films with 5 nm thickness were deposited at 200℃ on Si (001) substrates using plasma-enhanced atomic-layer deposition for gate dielectric applications. While TiO_2 films deposited on Si substrates are crystallized at an annealing temperature of 500℃, Ga_2O_3-TiO_2 nanomixed films show an incipient crystallization at 950℃ and exhibited a good thermal stability even at about 950℃ for 1 min. The dielectric constant of TaN/Ga_2O_3-TiO_2/Si capacitors is larger than that of TaN/TiO_2-Ga_2O_3/Si capacitors in nanomixed films annealed at 900℃ for 1 min. The EOT of the TaN/Ga_2O_3-TiO_2/Si capacitors was ～6 A up to an annealing temperature of 700℃ but increases with increasing annealing temperature above 700℃ for 1 min. The TaN/Ga_2O_3-TiO_2/Si capacitors annealed at 1000℃ exhibit a leakage current density of ～4 x 10~(-3)A/cm~2 at -1.5 V and an interfacial charge density of 1.5 x 10~(11) cm~(-2)eV~(-1). The Ga_2O_3-TiO_2 nanomixed films are new candidate materials for gate dielectric applications.