Hongsu Park, YoungWoong Moon and DuckKyun Choi Pages 16 - 19 ( 4 )
Using an a–InGaZnO(amorphous-IGZO) n-type semiconducting material, a vertically operating two terminal metalsemiconductor- ferroelectric-metal (MSFM) non-volatile resistive switching structure has been investigated. PZT thin film of composition Zr/Ti=10/90 was prepared by spin-coating method on the Pt/Ti/SiO2/p-Si(100) substrate, and 50 nm thick a-IGZO semiconductor thin film was deposited as a resistive layer by RF sputtering on the PZT layer. The fabricated coupling structure exhibited three orders of switching margin. At a reading voltage of 2.5V, the “on” current and “off” current were 2.6 x10-9A and 4.5 x10-12A respectively. Such an extremely low pico-level “on” current is determined by the leakage current of PZT and is attributed to the charge accumulation at the a- IGZO/PZT interface layer. On the other hand, the current level of the "off" state is associated with the charge depletion in the a-IGZO layer due to the polarity reversal in the PZT layer. The “on” current level observed in this study is about three orders of magnitude lower than the reported values of typical ferroelectric devices, indicating read speed might be slow. However, the potential for low power operating applications is still promising in the aspect that the increase the leakage current in PZT material is not as much difficult as decrease it.
a-IGZO, Ferroelectric, Non-volatile, PZT, Resistive switching.
Hanyang University, Department of Materials Science & Engineering, Seoul, Republic of Korea.