A low-temperature process to improve performances of a-In-Ga-Zn-O (a-IGZO) thin-film transistors (TFTs) fabricated at room temperature was examined Two deposition methods, pulsed laser deposition (PLD) and RF magnetron sputtering were employed to deposit the a-IGZO channels For the PLO case, the TFT characteristics were improved significantly by wet annealing at dew point (d p) of 50 degrees C at the annealing temperature of 200 degrees C For the sputtered TFTs, a wider range of annealing temperature from 100 to 200 degrees C was examined. It was found that annealing at >= 150 degrees C improved the TFT characteristics when dry annealing was employed On the other hand, wet annealing also improved mu(sat) and S values, but very large negative threshold voltage (V(th)) shift was observed These results indicate that the annealing at 150 degrees C is enough to obtain mobility (mu(sat)) as large as 8 cm(2) Vs(-1), but annealing temperature as high as 200 degrees C provides larger mu(sat) comparable to those obtained by 400 degrees C annealing It is speculated that the large negative V(th) shift originates from compensated donors in as-deposited sputtered films (C) 2009 Published by Elsevier B V