Abstract
The effect of niobium (Nb) doping on the performance and stability of TiOx -based thin-film transistors (TFTs) was studied. While sputtered TiOx has an initial amorphous phase and begins to crystallize to anatase at an annealing temperature of 450 °C, Nb-doped TiOx preserves the amorphous structure up to annealing temperatures as high as 550 °C. TFT devices fabricated using Nb-doped TiOx as the active layer exhibit higher field-effect mobility and better stability upon negative and positive bias stress compared to pure TiOx devices. X-ray photoelectron spectroscopy analyses indicate that Nb doping induces higher levels of oxygen deficiency and a considerable amount of defect states near the valence band, which cannot account for the higher device stability. It is thus suggested that the grain boundaries in crystalline TiOx TiO x may act as the major charge traps, which induce larger shifts in threshold voltage (Vth) upon bias stress.
Original language | English |
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Article number | 295102 |
Journal | Journal Physics D: Applied Physics |
Volume | 46 |
Issue number | 29 |
DOIs | |
State | Published - 24 Jul 2013 |