Record-high 2P <sub>r</sub> =60 μC/cm <sup>2</sup> by Sub-5ns Switching Pulse in Ferroelectric Lanthanum-doped HfO <sub>2</sub> with Large Single Grain of Orthorhombic Phase >38 nm
Tianyue Fu, Min Zeng, Shiyuan Liu, Honggang Liu, Ru Huang, Yanqing Wu
Abstract
In this work, we fabricate and characterize La-doped HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> ferroelectric capacitors to significantly improve the short pulse switching performance of hafnium-based ferroelectric technology. Systematic study of side-by-side comparison of typical Hf <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</inf> Zr$_{0.5} O_{2}$(HZO) and La-doped HfO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> (HfLaO) are carried out in terms of material properties, polarization switching using P-V loop and ultrafast pulse measurement, showing significant improvement of the HfLaO device. Single grain over 38 nm of orthorhombic phase in HfLaO is observed by TEM, providing a material basis for excellent ferroelectric switching. Large $2P_{r} = 63.4 \mu C /cm^{2}$ and record high current density over 2.5 A/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> per kHz in the HfLaO device has been demonstrated using P-V loop measurement. Furthermore, record-high $2P_{r} = 60 \mu C /$cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> is achieved under a very short pulse of 5 ns, twice higher than the previous record. A new parameter “switching conductivity G” is proposed to reflect the effectiveness of polarization switching. Record-high, voltage-independent $G= 1.03 \times 10^{4}S /$cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> has been obtained in our HfLaO devices owing to the large grain size with uniform switching properties.