Effect of annealing temperature on the properties of IZO films and IZO based transparent TFTs

This work shows the effect of the annealing temperature and atmosphere on the properties of r.f. magnetron sputtered indium-zinc oxide (IZO) thin-films of two types: one a conductive film (as-deposited, room temperature) that exhibits a resistivity of 3.5 x 10(-4) Q cm; the other, a semiconductor film with a resistivity similar to 10(2) Omega cm. The annealing temperatures were changed between 125 and 500 degrees C. Crystallization of the more conductive films was already noticeable at temperatures around 400 degrees C. Three different annealing atmospheres were used - vacuum, air and oxygen. For the conductive films, only the oxygen atmosphere was critical, leading to an increase of the electrical resistivity of more than one order of magnitude, for temperatures of 250 degrees C and above. Concerning the semiconductor films, both temperature and atmosphere had a strong effect on the film's properties, and the resistivity of the annealed films was always considerably smaller than the as-deposited films. Finally, some results of the application of these films to transparent TFTs are shown, (c) 2007 Elsevier B.V. All rights reserved.