Direct Growth of Bi₂SeO₅ Thin Films for High-k Dielectrics via Atomic Layer Deposition

This study describes a modified atomic layer deposition (ALD) process for fabricating BiOSe thin films, targeting their application as high-k dielectrics in semiconductor devices, especially for two-dimensional semiconductors. Using an intermediate-enhanced ALD technique for Bi₂Se₃ and a plasma-enhanced ALD process for Bi₂O₃, a method for the sequential deposition of Bi₂SeO₅ ternary films has been established. The thin film has been deposited on SiO₂ and TiN substrates, exhibiting growth rates of 0.17 to 0.16 nm·cycle^-1 without an incubation period, thanks to facile nucleation characteristics. The resulting film exhibited high flatness and reached 96% of its theoretical density, forming a uniform nanocrystalline structure. Electrical evaluations using metal-insulator-metal capacitors indicated the dielectric constant (∼17.6) and electrical breakdown strength (2.6 MV·cm^-1), demonstrating their potential as a dielectric layer.