Controlled-polarization-type ferroelectric gate thin film transistors (CP-type FeTFT) with nano-gap channel were fabricated by using a ZnO channel and a YMnO
3 ferroelectric film. The electrical properties of the epitaxially grown (0001)ZnO/(0001)YMnO
3 heterostructure fabricated by a pulsed laser deposition method were investigated by an impedance spectroscopy to discuss the carrier modulation by the spontaneous polarization of YMnO
3. It was found that the ZnO layer surrounding the top electrode has low resistivity. 100 nm-gap electrode was formed by an inclined deposition method on the ZnO/YMnO
3 heterostructure. The TFT showed non-volatile memory operation. However, the field-effect mobility is calculated to be 0.25 cm
2/Vs, which is ten times lower than that of the micro-channel TFT. The decrease of the resistivity of the ZnO layer surrounding the top electrode is a possible origin of the decrease of the field-effect mobility.
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