Electrical Properties Of Ta Research Articles

High ultraviolet transparent conducting electrodes formed using tantalum oxide/Ag multilayer

We investigated the optical and electrical properties of Ta 2 O 5 /Ag/Ta 2 O 5 films as functions of the thicknesses of the Ta 2 O 5 and Ag layers. It was found that with an increase in the thicknesses of the Ta 2 O 5 and Ag layers from 10 to 40 nm and from 12 to 24 nm, respectively, the sheet resistance, carrier concentration, electron mobility, and resistivity of the Ta 2 O 5 /Ag/Ta 2 O 5 film varied from 2.02 to 8.95 Ω/sq, 5.74 × 10 21 to 2.92 × 10 22 cm –3 , from 13.21 to 24.07 cm 2 /V·s, and from 8.89 × 10 -6 to 8.24 × 10 -5 Ω cm, respectively. The average transmittance ( T av ) of the multilayer samples ranged from 57.18% to 93.99%, and it depended on the Ta 2 O 5 and Ag layer thicknesses. The highest T av of 93.99% was observed for the film with 35 nm thick Ta 2 O 5 and 18 nm thick Ag layers, and the peak Haacke's figure of merit (157.04 × 10 –3 Ω –1 ) was obtained for 20 nm thick Ta 2 O 5 and 21 nm thick Ag layers. Ta 2 O 5 (100 nm) and Ta 2 O 5 /Ag/Ta 2 O 5 (20 nm/21 nm/20 nm) samples had optical bandgaps of 4.70 and 4.45 eV, respectively. Film Wizard simulations were conducted to understand the dependence of the transmittance of the multilayer on the thicknesses of the Ta 2 O 5 and Ag layers, and phasor analyses were performed to determine how the transmittance of the Ta 2 O 5 /Ag/Ta 2 O 5 (20 nm/21 nm/20 nm) film depended on the Ta 2 O 5 layer's thickness.

Rhombohedral–orthorhombic phase coexistence and electrical properties of Ta and BaZrO3 co-modified (K, Na)NbO3 lead-free ceramics

The BaZrO3 and Ta have been used to improve piezoelectric properties of (K, Na)NbO3 ceramics by the construction of the phase boundary, and (1 − x)K0.48Na0.52(Nb0.95Ta0.05)O3–xBaZrO3 [(1 − x)KNNT–xBZ] ceramics were prepared by the conventional solid-state method. The effect of BZ content on their phase structure, microstructure, and electrical properties has been investigated. A rhombohedral and orthorhombic phase coexistence has been observed in the compositional range of 0.05 ≤ x ≤ 0.07. With increasing BZ content, their Tc and To–t values decrease gradually, and the dielectric constant increases linearly. The ceramic with x = 0.06 exhibits an enhanced piezoelectric behavior (d33 ∼ 193 pC/N and kp ∼ 32.6%) because of the coexistence of two phases together with a dense microstructure. As a result, the construction of a rhombohedral and orthorhombic phase boundary is an effective way to improve the piezoelectric properties of KNN-based ceramics.

Electrical Properties of Ta(Si)N Films Prepared by Atomic Layer Deposition from Tert-Butylimido-Tris-Diethylamido Tantalum, Silane and Hydrogen Plasma

Ta(Si)N films were prepared by atomic layer deposition (ALD) from tert-butylimido-tris-diethylamido tantalum (TBTDET), triethylsilane, and activated hydrogen. Triethylsilane was used as an ancillary reducing agent and as a silicon precursor. The effects of the addition of the triethylsilane at different hydrogen plasma pulse times and power on the electrical properties, particularly stability in air, were investigated. Longer plasma pulse times with high power were effective in decreasing resistivity and increasing stability in air. However, introduction of silane resulted in an increase in resistivity of the films regardless of the hydrogen plasma conditions.

Processing and Electrical Properties of Ta and Li-Modified KNN-Based Lead-Free Thin Films Prepared by the RF Sputtering Technology

Lead-free potassium sodium niobate ceramic thin films were synthesized using rf magnetron sputtering technology for MFIS structures. The optimal sputtering parameters of the as-deposited KNN thin films for depositing times of 1h were obtained. Regarding the measured physical properties, the micro-structure and thickness of as-deposited KNN thin films for different oxygen concentration were obtained and compared by XRD patterns and SEM images. The surface roughness of KNN thin film was also observed by AFM morphology. The average grain size and root mean square roughness were 250 and 7.04 nm, respectively. For KNN thin films in the MFIS structure, the capacitance and leakage current density were 280 pF and 10-8A/cm2, respectively. We investigated that the leakage current density and the memory window increased, the capacitance critically increased as the oxygen concentration increased from 0 to 40%. However, the excess oxygen concentration process was decreased the electrical and physical of as-deposited KNN thin film. The effect of oxygen concentration on the physical and electrical characteristics of KNN thin films was investigated and determined.

The Structural and Electrical Properties of Ta<sub>2</sub>O<sub>5</sub> Thin Films Prepared by DC Sputtering Method

The Structural and Electrical Properties of Ta<sub>2</sub>O<sub>5</sub> Thin Films Prepared by DC Sputtering Method

Structural and electrical properties of Ta 2 O 5 thin films prepared by photo-induced CVD

Tantalum oxide (Ta 2 O 5 ) films and Al/Ta 2 O 5 /Si MOS capacitors were prepared at various powers by ultraviolet photo-inducing hot filament chemical vapour deposition (HFCVD). Effects of ultraviolet light powers on the structure and electrical properties of Ta 2 O 5 thin films were studied using X-ray diffraction (XRD) and atomic force microscopy (AFM). The dielectric constant, leakage current density and breakdown electric field of the samples were studied by the capacitance–voltage (C–V) and current–voltage (I–V) measurements of the Al/Ta 2 O 5 /Si MOS capacitors. Results show that the Ta 2 O 5 thin films grown without inducement of UV light belong to amorphous phase, whereas the samples grown with inducement of UV-light belong to δ-Ta 2 O 5 phase. The dielectric constant and leakage current density of the Ta 2 O 5 thin films increase with increasing powers of the UV- lamps. Effects of UV- lamp powers on the structural and electrical properties were discussed.

Ta/Si Schottky diodes fabricated by magnetron sputtering technique

Electrical properties of Ta/ n-Si and Ta/ p-Si Schottky barrier diodes obtained by sputtering of tantalum (Ta) metal on semiconductors have been investigated. The characteristic parameters of these contacts like barrier height, ideality factor and series resistance have been calculated using current voltage ( I– V) measurements. It has seen that the diodes have ideality factors more than unity and the sum of their barrier heights is 1.21 eV which is higher than the band gap of the silicon (1.12 eV). The results have been attributed the effects of inhomogeneities at the interface of the devices and native oxide layer. In addition, the barrier height values determined using capacitance–voltage ( C– V) measurements have been compared the ones obtained from I– V measurements. It has seen that the interface states have strong effects on electrical properties of the diodes such as C– V and R s – V measurements.

Physical and electrical properties of Ta–N, Mo–N, and W–N electrodes on HfO2 high-k gate dielectric

The influence of various types of metal nitride gate electrodes, i.e., tantalum nitride, molybdenum nitride, and tungsten nitride, on electrical characteristics of metal-oxide-semiconductor capacitors with hafnium oxide as the gate dielectric material has been studied. The result shows that both the physical and electrical properties of the high-k gate stack are influenced by the gate electrode materials and the post-metal-annealing temperature. Both the physical thickness and equivalent oxide thickness of the gate stack increased after the high-temperature N2 annealing step. The leakage current density decreased with the increase of the annealing temperature from 600to800°C. The work functions of these metal nitride electrodes decreased with the annealing temperature due to the variance of microstructure and chemical composition, as indicated by x-ray diffraction and second-ion-mass spectroscopy data. These metal nitride electrodes are suitable for n-channel metal-oxide-semiconductor device applications after 800°C N2 annealing because their work functions are between 4.05 and 4.25eV. The interface state density and oxide trap density of the high-k gate stack were also reduced by the high-temperature N2 annealing step.

Reliability comparison of tantalum and niobium solid electrolytic capacitors

This paper deals with a comparative investigation of tantalum and niobium solid electrolytic capacitors. Nb is an attractive replacement for Ta in solid electrolytic capacitors because it is lighter and cheaper than Ta. Although these two metals have much in common in their crystalline structure and physical and chemical properties, the electrical properties of Ta and Nb capacitors are different. Particularly, most Nb capacitors are characterized by an increase in direct current leakage during life testing. This causes parametric failure of Nb capacitors. On the other hand, the direct current leakage of Ta capacitors does not change significantly for a long time, but then increases sharply for some samples. Hence occasional catastrophic failures are typical for Ta capacitors. Nevertheless, the properties of high-CV Ta capacitors with low and high rated voltage approach the properties of Nb capacitors. The physical nature of these phenomena is discussed. © 1998 John Wiley & Sons, Ltd.

Electrical properties of Ta2O5 films obtained by plasma enhanced chemical vapor deposition using a TaF5 source

High quality Ta2O5 thin films have been obtained from TaF5 and O2 using a microwave excited electron cyclotron resonance plasma at low pressure (∼2 mTorr). Physical and electrical measurements reveal that the as-deposited amorphous films have excellent properties: refractive indices ∼2.16, dielectric constants ∼25, and leakage currents <10−10 A cm−2 at 2.5 V (0.3 MV cm−1, 85 nm thick, 13 nm SiO2 equivalent). Trapping and conduction properties of these layers have also been investigated, showing a reversible electron trapping and a trap-limited Poole–Frenkel effect.

Influence of additives on the electrical properties of dense SnO2-based ceramics

Highly densified 0.99 SnO2-0.01 CuO-based ceramics with antimony, tantalum, or niobium oxides as additives have been prepared. Samples have been characterized by dc conductivity and complex impedance spectroscopy as a function of temperature and by current density as a function of electric field. Microstructures have been analyzed by scanning electron microscopy, electron microprobe, and Auger spectroscopy. The electrical properties of Ta- and Nb-doped ceramics are grain boundary controlled at least at low temperature. Sb-doped materials show a different electrical behavior due to the presence of a segregation layer of antimony which inhibits grain boundary effects.

Structural and electrical properties of Ta and Ta nitrides deposited by chemical vapour deposition

It has been shown that single-phase α-Ta, β-Ta, Ta 2N, TaN(f.c.c.) and Ta 3N 5 films can be produced by chemical vapour deposition (CVD). The structure of the microcrystalline deposits has been investigated by transmission electron microscopy. Electrical measurements reveal that the resistivities of CVD films are comparable with those of sputtered films. However, the temperature coefficient of resistivity (TCR) of β-Ta, Ta 2N and TaN(f.c.c.) is positive, varying between 30 and 300 ppm K . In the case of Ta 3N 5 the TCR is negative ( α∼−40 000ppm K ) and the resistivity has a value of about 6 μ cm.