Effect of channel layer thickness on the performance of indium-zinc-tin oxide thin film transistors manufactured by inkjet printing.

We report the fabrication of high field-effect mobility of ∼110 cm(2)/(V s) for inkjet printed indium-zinc-tin oxide (IZTO) thin film transistors (TFTs). It is found that the morphology of IZTO material deposited by inkjet printing depends strongly on its thickness. When the thickness is 35 nm, IZTO is an homogeneous amorphous material and the TFT exhibits mobility over 100 cm(2)/(V s) and on/off current ratio of >10(6). However, when the thickness is 85 nm, IZTO has a two layer structure of homogeneous and heterogeneous materials and thus the TFT exhibited a mobility of ∼20 cm(2)/(V s). When the thickness is 800 nm, the morphology is porous and heterogeneous and thus the on/off current ratio is less than 1 × 10(3) and its mobility is ∼14 cm(2)/(V s). It is concluded therefore that homogeneous amorphous IZTO TFT on Al2O3 gate insulator can show high mobility, which can be achieved by thin layer formation by inkjet printing.