1. Ferroelectricity in dopant-free HfO2 thin films prepared by pulsed laser deposition
- Author
-
Jiyan Dai, Xubing Lu, Xingsen Gao, Yongjian Luo, Min Zeng, Minghui Qin, Deyang Chen, Chao Chen, Jun-Ming Liu, Guofu Zhou, Zhen Fan, Xiaozhe Yin, and Zhenxun Tang
- Subjects
Materials science ,Dopant ,Ferroelectricity ,Annealing (metallurgy) ,business.industry ,Metals and Alloys ,Pulsed laser deposition ,Dielectric ,Surfaces, Coatings and Films ,Electronic, Optical and Magnetic Materials ,TA401-492 ,Optoelectronics ,Deposition (phase transition) ,Thin film ,business ,Layer (electronics) ,Materials of engineering and construction. Mechanics of materials ,Orthorhombic phase ,Hafnium oxide - Abstract
As a high-k material, hafnium oxide (HfO2) has been used in gate dielectrics for decades. Since the discovery of polar phase in Si-doped HfO2 films, chemical doping has been widely demonstrated as an effective approach to stabilize the ferroelectric phase in HfO2 based thin films. However, the extra capping layer deposition, post-growth annealing and wake-up effect are usually required to arouse the ferroelectricity in HfO2 based thin films, resulting in the increase of complexity for sample synthesis and the impediment of device application. In this study, the ferroelectricity is observed in non-capped dopant-free HfO2 thin films prepared by pulsed laser deposition (PLD) without post-growth annealing. By adjusting the deposited temperature, oxygen pressure and thickness, the maximum polarization up to 14.7 μC/cm2 was obtained in 7.4 nm-thick film. The fraction of orthorhombic phase, concentrations of defects and size effects are considered as possible mechanisms for the influences of ferroelectric properties. This study indicates that PLD is an effective technique to fabricate high-quality ferroelectric HfO2 thin films in the absence of chemical doping, capping layer deposition and post-growth annealing, which may boost the process of nonvolatile memory device application.
- Published
- 2022