Modulation of the operational characteristics of amorphous InGaZnO thin-film transistors by In ₂O ₃ nanoparticles

The structure of thin-film transistors (TFTs) based on amorphous InGaZnO (a-IGZO) was modified by spin coating a suspension of In ₂O ₃ nanoparticles on a SiO ₂/p ⁺⁺ Si layered wafer surface prior to the deposition of IGZO layer by room-temperature sputtering. The number of particles per unit area (surface density) of the In ₂O ₃ nanoparticles could be controlled by applying multiple spin coatings of the nanoparticle suspension. During the deposition of IGZO, the In ₂O ₃ nanoparticles initially located on the substrate surface migrated to the top of the IGZO layer indicating that they were not embedded within the IGZO layer, but they supplied In to the IGZO layer to increase the In concentration in the channel layer. As a result, the channel characteristics of the a-IGZO TFT were modulated so that the device showed an enhanced performance as compared with the reference device prepared without the nanoparticle treatment. Such an improved device performance is attributed to the nano-scale changes in the structure of (InO) _n ordering assisted by increased In concentration in the amorphous channel layer.