Engineering of Ferroelectric HfO2-ZrO2Nanolaminates.
In this work, the ferroelectric properties of nanolaminates made of HfO2and ZrO2were studied as a function of the deposition temperature and the individual HfO2/ZrO2layer thickness before and after electrical field cycling. The ferroelectric response was found to depend on the structure of the nanolaminates before any postdeposition annealing treatment. After annealing with a TiN cap, an "antiferroelectric-like" response was obtained from nanolaminates deposited in an amorphous state at a lower temperature, whereas a ferroelectric response was obtained from nanolaminates deposited at a higher temperature, where crystallites were detected in thick films before annealing. As the individual layer thicknesses were decreased, an increased lattice distortion and a concurrent increase in remanent polarization were observed from the nanolaminates deposited at high temperatures. After field cycling, nanolaminates deposited at lower temperatures exhibited an antiferroelectric-like to ferroelectric transition, whereas those deposited at higher temperatures exhibited a larger remanent polarization. Finally, we demonstrate that by leveraging the proper choice of process conditions and layer thickness, remanent polarizations exceeding those of the HfZrO4solid solution can be obtained.
Intermolecular, Inc. , 3011 N. 1st Street, San Jose 95134, California, United States.
Stephen L
http://orcid.org/0000-0002-0124-1418
SL
Weeks
Intermolecular, Inc. , 3011 N. 1st Street, San Jose 95134, California, United States.
Ashish
A
Pal
Intermolecular, Inc. , 3011 N. 1st Street, San Jose 95134, California, United States.
Vijay K
VK
Narasimhan
Intermolecular, Inc. , 3011 N. 1st Street, San Jose 95134, California, United States.
Karl A
KA
Littau
Intermolecular, Inc. , 3011 N. 1st Street, San Jose 95134, California, United States.
Tony
T
Chiang
ferroelectrics; hafnium oxide; nanolaminates; nonvolatile memory; wake up