Lim Seokwon, Ahn Yeonghwan, Won Beomho, Lee Suwan, Park Hayoung, Kumar Mohit, Seo Hyungtak
Department of Energy Systems Research, Ajou University, Suwon 16499, Republic of Korea.
Department of Materials Science & Engineering, Ajou University, Suwon 16499, Republic of Korea.
Nanomaterials (Basel). 2024 Aug 25;14(17):1386. doi: 10.3390/nano14171386.
In this study, the effect of annealing and substrate conditions on the ferroelectricity of undoped hafnium oxide (HfO) was analyzed. Hafnium oxide was deposited on various substrates such as platinum, titanium nitride, and silicon (Pt, TiN, Si) through RF magnetron sputtering. Annealing was performed in a nitrogen atmosphere at temperatures ranging from 400 to 600 °C, and the process lasted anywhere from 1 to 30 min. As a result, it was confirmed that the orthorhombic phase, the main cause of ferroelectricity, was dominant after a post-anneal at 600 °C for 30 min. Additionally, it was observed that interface mixing between hafnium oxide and the substrate may degrade ferroelectricity. Accordingly, the highest remanent polarization, measured at 14.24 μC/cm, was observed with the Pt electrode. This finding was further corroborated by piezo force microscopy and endurance tests, with the results being significant compared to previously reported values. This analysis demonstrates that optimizing substrate and annealing conditions, rather than doping, can enhance the ferroelectricity of hafnium oxide, laying the foundation for the future development of ferroelectric-based transistors.
在本研究中，分析了退火和衬底条件对未掺杂氧化铪（HfO）铁电性的影响。通过射频磁控溅射将氧化铪沉积在各种衬底上，如铂、氮化钛和硅（Pt、TiN、Si）。在氮气气氛中于400至600°C的温度范围内进行退火，过程持续1至30分钟。结果证实，作为铁电性主要原因的正交相在600°C退火30分钟后占主导地位。此外，观察到氧化铪与衬底之间的界面混合可能会降低铁电性。因此，使用铂电极时观察到最高剩余极化强度，测量值为14.24μC/cm²。压电显微镜和耐久性测试进一步证实了这一发现，与先前报道的值相比，结果具有显著性。该分析表明，优化衬底和退火条件而非掺杂，可以增强氧化铪的铁电性，为基于铁电的晶体管的未来发展奠定了基础。
