Temperature-Dependent Operation of InGaZnO Ferroelectric Thin-Film Transistors With a Metal-Ferroelectric-Metal-Insulator- Semiconductor Structure

We report the temperature-dependent operation of back-end-of-line (BEOL) compatible amorphous indium-gallium-zinc-oxide (
${a}$
-IGZO) ferroelectric thin-film transistors (FeTFTs) with a large memory window (MW) more than 3 V. Our
${a}$
-IGZO FeTFTs have a metal–ferroelectric–metal–insulator–semiconductor (MFMIS) stru- cture with Zr-doped HfO
₂
(HZO) as the ferroelectric layer. Characteristics of
${a}$
-IGZO FeTFTs are investigated in the temperature range of −40 °C to 100 °C. We found that: Firstly, the remanent polarization (
${P}_{\text {r}}$
) of the HZO film increases with
$2{P}_{\text {r}}$
from
$\sim 35~ {\mu }\text{C}$
/cm
²
at −40 °C to
$\sim 40~ {\mu }\text{C}$
/cm
²
at 100 °C. Secondly, enhancement in MWs at high temperatures is observed, achieving MWs larger than 3.5 V when the temperature is higher than 60 °C. Thirdly, for the threshold voltage (
${V}_{\text {TH}}$
) at high temperatures, there is a competition between the negative shift caused by higher carrier concentration in the
${a}$
-IGZO channel and positive shift due to the charge trapping at the floating gate in the MFMIS structure. This could be explored to realize good
${V}_{\text {TH}}$
stability.