Effect of aluminum addition to solution-derived amorphous indium zinc oxide thin film for an oxide thin film transistors

Abstract

Aluminum-doped indium zinc oxide (IZO) thin film transistors (TFTs) were fabricated to examine the effect of aluminum incorporation in the solution-derived channel layer of TFTs. The IZO channel layer containing aluminum was amorphous. The addition of aluminum suppressed the carrier concentration of the channel layer and affected the electrical characteristics of the TFTs. The bottom-gate TFTs were manufactured on highly doped n-type silicon wafers coated with a SiO2 layer as a gate insulator. An aluminum-doped IZO solution was spin coated on the SiO2 layer and annealed in air. The molar ratio of aluminum-versus-indium-versus zinc was changed to determine the optimized molar ratio of a channel layer of TFTs depending on the annealing temperature and layer thickness. The optimized aluminum-doped indium zinc oxide TFTs exhibited a high on/off current ratio of ∼3.0 × 106, a threshold voltage of ∼2 V and a low subthreshold swing of 0.76 V/dec, respectively.