Defect passivation and homogenization of amorphous oxide thin-film transistor by wet O2 annealing

Roles of H2O addition to an annealing atmosphere were investigated for amorphous In-Ga-Zn-O thin-film transistors fabricated at room temperature. Although dry O-2 annealing improved saturation mobility (mu(sat)) and subthreshold voltage swings (S), wet O-2 annealing further improved them to mu(sat)similar to 12 cm(2)(V s)(-1) and S < 0.12 V decade(-1) along with improvement of their uniformity. Desorption of OH-related species caused conductivity increase during thermal annealing at < 310 degrees C. Zn-O components started to desorb at similar to 300 degrees C for the unannealed and the dry O-2 annealed films, while these were suppressed remarkably by the wet O-2 annealing.