Ferroelectric-gate thin-film transistors using indium-tin-oxide channel with large charge controllability

We have fabricated and characterized ferroelectric-gate thin-film transistors (TFTs) using indium-tin-oxide (ITO) as a channel and ferroelectric Bi4−xLaxTi3O12 (BLT) as a gate insulator. We have obtained a typical n-channel transistor property with clear current saturation in drain current and drain voltage (ID–VD) characteristics. The obtained on∕off current ratio is more than 104 and the field-effect mobility is estimated 9.1cm2∕Vs. In particular, we demonstrate a large “on”-current of 2.5 mA in ITO∕BLT structure TFT in spite of the low channel mobility. This is because the ferroelectric film can induce large charge density due to the spontaneous polarization.