Nanostructures Stacked on Hafnium Oxide Films Interfacing Graphene and Silicon Oxide Layers as Resistive Switching Media

• Published in: Nanomaterials (Basel, Switzerland) Vol. 13; no. 8; p. 1323
• Main Authors: 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
• Format: Journal Article
• Language: English
• Published: Switzerland MDPI AG 09-04-2023; MDPI
• Subjects: atomic layer deposition; Atomic layer epitaxy; Chemical vapor deposition; Dielectrics; Electron beams; Evaporation; Graphene; Graphite; Hafnium; Hafnium oxide; Interlayers; Metal foils; Metal oxides; Nanostructure; Oxide coatings; Plasma; Quantum dots; Raman spectroscopy; Random access memory; resistive switching; Silicon; Silicon dioxide; Silicon oxide; Silicon oxides; Silicon substrates; stacked nanostructures; Switching; Thickness; United States > US; hafnium oxide; silicon oxide; stacked nanostructures; atomic layer deposition; resistive switching; graphene
• ISSN: 2079-4991; 2079-4991
• 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.