Studies on Nd_xIn_1−xO₃ semiconducting thin films prepared by rf magnetron sputtering

Neodymium-substituted indium oxide (Nd_xIn_1−xO₃, NIO) semiconducting thin films fabricated by rf sputtering were investigated. It was found that the incorporation of Nd atoms would lead to broadening the optical band gap, suppressing the grain growth, and reducing the free carrier concentration. The field-effect transistors with different NIO (5%, 15%, and 25% Nd concentration of the targets) channel layers exhibited similar electrical stability under positive gate-bias-stress, but the ones with 15% and 25% Nd concentration displayed much better stability under negative gate-bias-stress. Detailed studies showed that the content of |Nd3d_5/2⁵4f⁴O2p⁻¹> electron configuration decreased as the Nd concentration increased, resulting in the reduction of holes during negative-bias-stress. And the reduction of the |Nd3d_5/2⁵4f⁴O2p⁻¹> content as the Nd concentration increased was ascribed to less overlap between the metal and ligand orbitals arose from large lattice expansion.