Turn-On voltage modulation of Indium-Gallium-Zinc-Oxide thin-film transistors through thermal annealing processes

The characteristics of metal-oxide-based thin-film transistors (TFTs) are known to have strong relations with the thermal processes they have gone through. Particularly, the resistivity of the indium-gallium-zinc-oxide (IGZO) film is sensitive to the annealing atmosphere, temperature and cover permeability. A new way of modulating turn-on voltage (V_on) was proposed by controlling the annealing processes of TFT. The devices will change from enhancement mode to depletion mode with negative V_on shift of several volts if they are annealed in nitrogen (N₂), due to the decreased channel resistivity. And such shift can be recovered in an oxidizing annealing. Considering the absence of high performance p-type metal-oxide TFTs, this new method can be used to construct logic circuit based on enhancement and depletion mode n-type TFTs, exhibiting great potential in assembling system-on-panel application.