posted on 2024-01-03, 04:03authored bySoundararaj Annamalai, Gopalakrishnan Dayal, Jayesh Gondhalekar, Kochupurackal B. Jinesh
Titanium oxynitride (TiOxNy) thin films were successfully
coated
on silicon
and fluorine-doped tin oxide (FTO) glass substrates using an on-surface
plasma-enhanced atomic layer deposition technique. Depositions were
carried out using titanium tetrachloride (TiCl4) as a precursor
and oxygen–nitrogen plasma at various plasma powers. The structural
analyses of these films reveal that all deposited films are crystalline
in nature, exhibiting the formation of TiO2, TiOxNy, and TiN mixed phases.
Further elemental analysis of these films using X-ray photoelectron
spectroscopy reveals that with increasing plasma power, the nitrogen
content in the films starts increasing until 33 W and reduces again
at 48 W. Using the deposited films, artificial synapses were fabricated
with gold (Au) as the top electrodes, and the Au/TiOxNy/FTO devices emulate the functions
of biological neurons. The neuromorphic properties of the devices
were proportional to the nitrogen content of the films. These synaptic
devices exhibit the anti-Hebbian behavior of associative learning.
Furthermore, these devices were used for pattern recognition by training
it with a set of images and by testing it with a fresh set of images.
The pattern recognition accuracy is found to enhance significantly
in samples deposited by intermediate plasma power, where the nitrogen
content was the highest.