Thirty-Day-Long Data Retention in Ferroelectric-Gate Field-Effect Transistors with HfO2 Buffer Layers

概要

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Metal–ferroelectric–insulator–semiconductor (MFIS) diodes and p-channel MFIS field-effect transistors (FETs) were fabricated and their electrical properties were characterized. These MFIS structures were formed using HfO2 as an insulating buffer layer, and SrBi2Ta2O9 (SBT) and (Bi,La)4Ti3O12 (BLT) as ferroelectric films. HfO2 buffer layers of about 8 nm physical thickness were deposited by ultrahigh-vacuum (UHV) electron-beam evaporation, then ferroelectric films of about 400 nm thickness were deposited by sol–gel spin coating. The fabricated p-channel MFIS-FETs with the SBT/HfO2 gate structure exhibited a drain current on/off ratio larger than $10^{3}$ even after 30 days had elapsed. It was also found that the degradation of ferroelectricity was not pronounced even after applying $2.2\times 10^{11}$ bipolar pulses.
Published by the Japan Society of Applied Physics through the Institute of Pure and Applied Physicsの論文
2005-08-15