Comparison of Electrolyte Performance for Ta[sub 2]O[sub 5] Thin Films Produced by Pulsed and Continuous Wave PECVD

Abstract

Tantalum oxide films were deposited by pulsed and continuous wave ͑CW͒ plasma-enhanced chemical vapor deposition ͑PECVD͒. The pulsed films were stoichiometric and free of impurities as measured by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. CW films contained significant amounts of hydroxyl impurities, resulting in a nonstoichiometric composition with an O/Ta ratio of ϳ2.8. Impedance spectroscopy was used to quantify ion transport through electrochromic half-cells formed by depositing tantalum oxide on both tungsten and vanadium oxides. Logarithmic plots of the imaginary component of impedance vs frequency were employed to extract equivalent circuit parameters. Despite the differences in composition the pulsed and CW films displayed similar ionic conductivities, with values of ϳ6 ϫ 10 −10 and ϳ2 ϫ 10 −10 S/cm for H + and Li + , respectively. However, the pulsed PECVD films displayed dramatically reduced electrical leakage. The ratio of ion/ electron conductivity exceeded 100 for pulsed PECVD films, while ion / e was Ͻ1 in CW material.

Enhancement of metal oxide deposition rate and quality using pulsed plasma-enhanced chemical vapor deposition at low frequency

“…The tantala films were deposited using pentaethoxy tantalum in a capacitively coupled reactor as described previously. 15,30 The ZnO was formed from dimethyl zinc in a remote PECVD configuration formerly used for alumina deposition. 16,19 The residence time in both systems ͑ ϳ 4 s͒ precluded the use of short cycles required for high rate synthesis, but the dramatic benefits of pulsed operation for film quality are readily apparent.…”

Enhanced lithium-ion intercalation and conduction of transparent tantalum oxide films by lithium addition with an atmospheric pressure plasma jet

“…For the TaOx films deposited onto rigid glass/ITO substrates by plasmaenhanced chemical vapor deposition, a deposition rate of 0.167 nm/s is produced [15]. Thus, this study reports a simple novel, one-step deposition method with rapid depositions of TaOyCz, LixTaOyCz, and LiOyCz films onto flexible PET/ ITO substrates via an APPJ at CLB (%) of 0-100 %.…”

“…However, lithium added into TaOyCz films as the CLB increased to 19 % causes the Li + ionic conductivity to decrease to 50.4 × 10 −10 S/cm. The Li + ionic conductivity of pulsed and continuous wave PECVD-produced TaOy films with a value of ∼2 × 10 −10 S/cm is reported for utilization as an electrolyte in EC devices [15]. The Li + ionic conductivity with a value of 2 × 10 −8 S/cm for atomic layer deposition of LixTaOy films is stated as the solid-state electrolytes used for microbatteries [32].…”

“…The Li + ion conduction of TaO x thin films has been investigated for EC devices [14]. Seman et al reported that Li + ion conduction (Li + ionic conductivity of 3 × 10 −10 S/cm) is about one half lower than proton conduction (H + protonic conductivity of 6 × 10 −10 S/cm) through TaO x thin films [15]. To enhance Li + ion conduction in TaO x thin films, titanium oxide (TiO x ) [16] and zinc oxide (ZnO x ) [17] films have been added into TaO x thin films.…”

Reversible resistance switching properties in Ti-doped polycrystalline Ta2O5 thin films

“…Among them, the proposition of the formation and rupture of the filament conductive paths which consist of oxygen vacancies or metallic ions in the insulating matrix appears to be one of the most plausible. When it comes to Ta 2 O 5 films, stoichiometric Ta 2 O 5 films could be used as high-k dielectric materials [12] while nonstoichiometric Ta 2 O 5 films could be used as solid electrolytes [13], which involve the participation of oxygen vacancies and conducting ions. Therefore, the RS properties of Ta 2 O 5 films are expected, and some attention has been paid to them [14].…”