Effect of Carrier Transport Process on Tunneling Electroresistance in Ferroelectric Tunnel Junction

We demonstrate the factors that determine the tunneling electroresistance (TER) of the ferroelectric tunnel junction (FTJ) by investigating the effects of temperature ( <tex-math notation="LaTeX">T </tex-math> ) and the number of cycles ( <tex-math notation="LaTeX">N) </tex-math> on remnant polarization ( <tex-math notation="LaTeX">Pᵣ) </tex-math> and carrier transport process. The fabricated FTJs have a metal/ferroelectric/insulator/semiconductor structure. The <tex-math notation="LaTeX">Pᵣ </tex-math> is increased with increasing <tex-math notation="LaTeX">T </tex-math> and <tex-math notation="LaTeX">N </tex-math> due to oxygen vacancy redistribution. However, the increased <tex-math notation="LaTeX">Pᵣ </tex-math> in a higher <tex-math notation="LaTeX">T </tex-math> and <tex-math notation="LaTeX">N </tex-math> does not improve the TER ratio. Using current-voltage characterization and low-frequency noise spectroscopy, we reveal that the carrier transport process at the interface between the ferroelectric and dielectric layers becomes more important than <tex-math notation="LaTeX">Pᵣ </tex-math> in determining the TER ratio.