High Performance Schottky Barrier TFTs With Indium–Gallium–Zinc-Oxide/Mo Schottky Junction

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> <tex-math notation="LaTeX">$10^{-8}$ </tex-math></inline-formula> Acm<inline-formula> <tex-math notation="LaTeX">${}^{-{2}}$ </tex-math></inline-formula>) are achieved. The field effect mobility is ~102.58 cm<inline-formula> <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.

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