Insight into the plasma oxidation process during pulsed laser deposition

Abstract

The dynamics of transient plasmas generated by ns laser ablation of Ag targets under various O 2 gas pressures (10 −5 -10 Pa) were investigated by implementing angle-and time-resolved Langmuir probe (LP) analysis and space-and timeresolved optical emission spectroscopy (OES). The effects of an O 2 atmosphere on silver oxide formation and the ionic kinetics and the overall plasma energy were systematically investigated. Measurements performed in the LP floating regime revealed the presence of three-ionic structures with kinetic energies varying from 0.8 to 350 eV, which can be tailored by the addition of O 2 . The timemodulated regime of electron temperature in the 0.5-3 eV observed for pressures higher than 2 Pa of O 2 could be explained by the formation and dissociation of silver oxide molecules. The energetic balance sustains molecular oxide formation, as confirmed by OES measurements, which revealed emission signatures of AgO (B 2 Π 3/2 and X 2 Π 3/2 ) in the 350 nm (B 2 Π 3/2 ) and 460 nm (X 2 Π 3/2 ) spectral regions. Finally, thin films were deposited to understand the range of possibilities offered by pulsed laser deposition of Ag in O 2 . The morphology and atomic structure of the films were analysed for large-scale deposition. Silver oxides were detected in the films starting from 2 Pa, while at higher values, we found mixtures of different Ag x O y phases. A cauliflower-like morphology was dominant above 5 Pa of O 2 atmosphere pressures, which signals the formation of the AgO phase in the deposited film. Our results demonstrate that the properties of deposited thin films are influenced by plasma properties.

Subthreshold Laser Ablation Measurements by Langmuir Probe Method for ns Irradiation of HfO2 and ZrO2

“…Similar functions for ablation threshold determination have been proposed [ 5 , 15 , 32 ] by using the ablation crater area or ablation depth. The values obtained, 0.87 J/cm 2 for HfO 2 and 0.5 J/cm 2 for ZrO 2 , as seen in Figure 3 , are slightly below other reports from the literature [ 5 , 33 , 34 ]. This is due to the sensitivity of the technique, especially considering the exponential increase in charge current and the appearance of high kinetic ionic peaks and the lower quality of the surface morphology.…”

“…A more in-depth analysis of charge current temporal trace can be done by following the approaches previously used by our group in [ 34 , 35 ] and by Torrisi in [ 36 , 37 , 38 ], by knowing the irradiation conditions and a series of basic plasma parameters information on the electron and atomic density, as well as the Debye length. When representing these parameters as a function of the laser fluence ( Figure 7 a–d), some important dependences can be seen.…”

On the Deposition Process of Ceramic Layer Thin Films for Low-Carbon Steel Pipe Protection

“…The three-parametric dependence will also be reflected in the expansion velocities of the plasma. As reported by our group in [31][32][33][34], the inner structure of the plasma can have a complex of two or more substructures which forms during expansion. Comparing the geometries of the two plasmas during the deposition process, we observ that the C1 plasma has a more elongated shape reaching the substrate (visible emission contribution to the understanding of the plasma volume) after 500 ns, whereas C2 takes approximately 1 µs having a more compact shape in the first stage of expansion.…”

Light- and Pressure-Stimulated Silver Oxide (AgOx)-Based Memristors for In-Sensor Memory and Computing Applications

“…AgO, Ag 3 O 4 , Ag 2 O, and Ag 2 O 3 are the most common phases of silver oxide; among them, AgO and Ag 2 O are the most thermodynamically stable oxides of silver. , Among the other phases of silver oxide, Ag 2 O has p-type semiconducting properties and shows optical absorption under the visible light range . DC sputtering, electron beam evaporation, thermal oxidation, , and pulsed laser deposition are some of the standard methods for growing silver oxide thin films. Hence, there is a need to study and explore this material’s memristive nature and its sensing ability for a low-cost and energy-efficient future memristive device for possible neuromorphic computing applications. ,, …”