Polycrystalline In‐Ga‐O Thin‐Film Transistor With Field‐Effect Mobility Over 40 cm ² /Vs—Mobility Modeling and Self‐Heating Simulation

A polycrystalline In‐Ga‐O (poly‐IGO) thin‐film transistor (TFT) with field‐effect mobility ( μ FE ) over 40 cm 2 /Vs has been developed and analyzed by mobility modeling and self‐heating simulation. The μ FE is the highest among metal–oxide semiconductor (OS) TFTs using common semiconductor materials and mature production processes. Moreover, the subthreshold swing (S) is 0.13 V/dec, and the threshold voltage (Vth) is 0.0 V, which are also superior. These excellent characteristics are accomplished by inherent features of the polycrystalline phase and IGO material. The mobility modeling is executed by the modeling procedure once we developed and clarifies that due to a behavior of potential barriers at grain boundaries, the intrinsic mobility ( μ ) positively depends on the carrier density ( n ), which enhances the μ FE . The μ‐n dependence can be a universal curve and is indispensable to design devices and circuits in the future. Moreover, the self‐heating simulation is executed by implementing the T‐dependent μ‐n dependence and clarifies that the μ slightly but also positively depends on the temperature ( T ), which also enhances μ FE . We expect that poly‐IGO TFTs can replace amorphous In‐Ga‐Zn‐O ( α ‐IGZO) TFTs in the near future.