Effects of Hf incorporation on indium zinc oxide thin-film transistors using solution process

Abstract

Thin-film transistors (TFTs) were fabricated by employing amorphous hafnium indium zinc oxide (HIZO) thin films as the active channel layer by the solution process. Thermogravimetry-differential thermal analysis, transmittance measurements, atomic force microscopy, scanning electron microscopy, x-ray diffraction, and Fourier transform infrared analysis were used to study the formation, structure, and optical properties of the HIZO films. The results showed that the addition of Hf to the IZO system resulted in suppression of carrier generation. The HIZO TFTs exhibited lower off-currents and higher onoff current ratios than IZO TFTs without Hf doping. HIZO TFTs with a Hf doping content of 5 at. % obtained a threshold voltage of 3.7 V, a mobility of 0.27 cm2 V-1 s-1, a subthreshold swing of 1.2 V/dec, and an on-off current ratio of 106.