Affiliation:
1. University Grenoble Alpes, CNRS, CEA/LETI-Minatec, Grenoble INP, LTM, 38054 Grenoble, France
Abstract
Sub-10 nm thick gadolinium-doped hafnia (Gd:HfO2) layers were grown in metal–insulator–metal (TiN/Gd:HfO2/TiN) stacks using a plasma-enhanced atomic layer deposition process. Thermally annealed Gd:HfO2 layers with a thickness of 8.8, 6.6, and 4.4 nm exhibited orthorhombic crystalline structure and showed ferroelectric properties. Indeed, polarization vs electric field hysteresis loops were recorded with 2P r polarization ranging from 2 to 20 μC/cm2. The studied layers showed the same coercive electric field (∼2 MV/cm). Consequently, polarization switching voltage between +P r and −P r decreased down to 0.9 V for the thinnest layer. Remanent polarization cycling showed a strong wake-up effect, with no fatigue, up to 109, followed by a stabilization up to 1010 cycles, where 2P r reached 33 μC/cm2 for 8.8 nm Gd:HfO2. This endurance result and the absence of noticeable remanent polarization fatigue can be attributed to the optimal chemical composition of the TiN/Gd:HfO2 interface, which is supposed to be at the origin of defect generation, mostly oxygen vacancies, that leads to ferroelectric polarization fatigue.
Subject
Physics and Astronomy (miscellaneous)
Cited by
6 articles.
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