Nano suboxide layer generated in Ta2O5 by Ar+ ion irradiation

Abstract

Ta2O5/TaOx heterostructure has become a leading oxide layer in memory cells and/or a bidirectional selector for resistive random access memory (RRAM). Although atomic layer deposition (ALD) was found to be uniquely suitable for depositing uniform and conformal films on complex topographies, it is hard to use ALD to grow suboxide TaOx layer. In this study, tantalum oxide films with a composition of Ta2O5 were grown by ALD. Using Ar+ ion irradiation, the suboxide was formed in the top layer of Ta2O5 films by observing the Ta core level shift toward lower binding energy with angle-resolved X-ray photoelectron spectroscopy. By controlling the energy and irradiation time of an Ar+ ion beam, Ta2O5/TaOx heterostructure can be reliably produced on ALD films, which provides a way to fabricate the critical switching layers of RRAM.

Low-Dimensional Polyoxometalate Molecules/Tantalum Oxide Hybrids for Non-Volatile Capacitive Memories

“…As seen in the right part of Figure , the O 1s peak can be analyzed in two peaks, with the first located at a binding energy of 530.7 ± 0.1 eV corresponding to oxygen bonded to tantalum in Ta 2 O 5 , in agreement to the literature and the other corresponding to oxygen related to surface contamination (532.0 ± 0.1 eV) . The main peak of Ta 4f7/2 is located at a binding energy of 26.4 ± 0.1 eV (Figure left), corresponding to tantalum bonded with oxygen in stoichiometric Ta 2 O 5 . , The higher binding energy peak of the 4f doublet appears at 28.4 eV and corresponds to Ta 4f5/2 in Ta 2 O 5 , according to literature. , In Figure , UV–vis absorption measurements indicate a shift of the Ta 2 O 5 absorption edge toward higher wavelengths upon POM deposition, indicating an effective narrowing of the gap. The characteristic POM peaks remain intact in the absorption spectrum of the composite material, indicating the integrity of the molecular structures.…”

Self-Rectifying Resistive Switching Memory with Ultralow Switching Current in Pt/Ta2O5/HfO2-x /Hf Stack

“…Additionally, it is worth noting from the XPS results in Fig. 2c that the binding energy of Ta 4f well coincided with the reported value of the Ta 4f peak (26.6 eV for Ta 4f7/2 and 28.4 eV for Ta 4f5/2) in Ta 2 O 5 [3, 8]. For HfO 2- x , grown by directly oxidizing the metal Hf via oxygen plasma with a duration 1600 s, the core-level Hf4f7/2–Hf4f5/2 was observed at an energy corresponding to the non-stoichiometric HfO 2 (12.7–18.5 eV) [9], which indicated the presence of the neutral oxygen vacancy in our HfO 2- x layer.…”

Hybrid molecular solid state memories and electronic nanodevices based on polyoxometalates and other molecules of reversible redox activity

“…As seen in the right part of Figure 4.7 the O1s peak can be analyzed in two peaks, with the first located at a binding energy of 530.7 ± 0.1eV corresponding to oxygen bonded to tantalum in Ta 2 O 5 , in agreement to the literature [287] and the other corresponding to oxygen related to surface contamination (532.0 ± 0.1eV ) [288]. The main peak of Ta4f7/2 is located at a binding energy of 26.4±0.1eV (Figure 4.7 left) corresponding to tantalum bonded with oxygen in stoichiometric Ta 2 O 5 [287,289]. The higher binding energy peak of the 4f doublet appears at 28.4 eV and corresponds to Ta4f5/2 in Ta 2 O 5 , according to literature [289,290].…”

“…The main peak of Ta4f7/2 is located at a binding energy of 26.4±0.1eV (Figure 4.7 left) corresponding to tantalum bonded with oxygen in stoichiometric Ta 2 O 5 [287,289]. The higher binding energy peak of the 4f doublet appears at 28.4 eV and corresponds to Ta4f5/2 in Ta 2 O 5 , according to literature [289,290].…”

“…The two peaks of the Ta4f doublet have a 4f7/2 -4f5/2 area ratio of 4:3 and energy separation of 1.9eV, the characteristic spacing of Ta4f, in accordance to [291,292]. The higher peak of the 4f doublet appears at 28.4 eV and corresponds to Ta4f5/2 in Ta 2 O 5 according to the literature [293,294,295]. XPS analysis of the 25 nm as-grown tantalum oxide indicates stoichiometric Ta 2 O 5 , with no formation of suboxides.…”