High Performance Schottky Barrier TFTs With Indium–Gallium–Zinc-Oxide/Mo Schottky Junction
Chen Wang, Chaofan Zeng, Wenmo Lu, Haiyue Ning, Fengnan Li, Fei Ma
Abstract
IGZO/Mo Schottky barrier TFTs are demonstrated, in which the tunable Schottky junction is formed between IGZO and Mo electrode after vacuum annealing at 280 °C or above. Oxygen-related trap states could be eliminated by vacuum annealing, and the pinning of Fermi level at IGZO/Mo interface is inhibited. The intrinsic IGZO/Mo Schottky barrier height is 0.37 eV. It can be further modulated from ~0.6 eV to ~0 eV as the gate voltage is changed, because the Fermi level of IGZO thin films can be adjusted by the external gate field. Large on-off ratio on the source-drain current (~106) and low off current density ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$10^{-8}$ </tex-math></inline-formula> Acm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${}^{-{2}}$ </tex-math></inline-formula> ) are achieved. The field effect mobility is ~102.58 cm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{{2}}\text{V}^{-{1}}\text{s}^{-{1}}$ </tex-math></inline-formula> , superior to the conventional IGZO TFTs. HfO2 passivation layer is utilized to suppress the diffusion of ambient O2 and thus enhance the stability of TFTs.