Kahro Tauno, Raudonen Kristina, Merisalu Joonas, Tarre Aivar, Ritslaid Peeter, Kasikov Aarne, Jõgiaas Taivo, Käämbre Tanel, Otsus Markus, Kozlova Jekaterina, Alles Harry, Tamm Aile, Kukli Kaupo
Institute of Physics, University of Tartu, W. Ostwaldi 1, 50411 Tartu, Estonia.
Nanomaterials (Basel). 2023 Apr 9;13(8):1323. doi: 10.3390/nano13081323.
SiO films were grown to thicknesses below 15 nm by ozone-assisted atomic layer deposition. The graphene was a chemical vapor deposited on copper foil and transferred wet-chemically to the SiO films. On the top of the graphene layer, either continuous HfO or SiO films were grown by plasma-assisted atomic layer deposition or by electron beam evaporation, respectively. Micro-Raman spectroscopy confirmed the integrity of the graphene after the deposition processes of both the HfO and SiO. Stacked nanostructures with graphene layers intermediating the SiO and either the SiO or HfO insulator layers were devised as the resistive switching media between the top Ti and bottom TiN electrodes. The behavior of the devices was studied comparatively with and without graphene interlayers. The switching processes were attained in the devices supplied with graphene interlayers, whereas in the media consisting of the SiO-HfO double layers only, the switching effect was not observed. In addition, the endurance characteristics were improved after the insertion of graphene between the wide band gap dielectric layers. Pre-annealing the Si/TiN/SiO substrates before transferring the graphene further improved the performance.
通过臭氧辅助原子层沉积法生长出厚度低于15纳米的SiO薄膜。石墨烯通过化学气相沉积在铜箔上，并通过湿化学方法转移到SiO薄膜上。在石墨烯层顶部，分别通过等离子体辅助原子层沉积或电子束蒸发生长连续的HfO或SiO薄膜。微拉曼光谱证实了在HfO和SiO的沉积过程之后石墨烯的完整性。设计了具有石墨烯层介于SiO与SiO或HfO绝缘层之间的堆叠纳米结构，作为顶部Ti和底部TiN电极之间的电阻开关介质。对有和没有石墨烯中间层的器件行为进行了比较研究。在有石墨烯中间层的器件中实现了开关过程，而在仅由SiO - HfO双层组成的介质中未观察到开关效应。此外，在宽带隙介电层之间插入石墨烯后，耐久性特性得到改善。在转移石墨烯之前对Si/TiN/SiO衬底进行预退火进一步提高了性能。
