Densification process and mechanism of solution-processed amorphous indium zinc oxide thin films for high-performance thin film transistors

Abstract

Although sol-gel IZO thin films are entirely porous, there are local dense regions at the surface and interface. From the relationship between the refractive index and thickness, we found that densified regions are maximized to the level of sputter thin films' density when the thickness is reduced. TFT devices with one-layer and four-layer IZO channels with the same thickness of 200 Å were compared. The four-layer channel showed a field-effect mobility of 9.06 cm2 V-1 s-1. This result shows an improvement of five times compared to the 1.95 cm2 V-1 s-1 of the one-layer channel, thus validating the effect of densification.