Zero Temperature Coefficient Of Resistivity Research Articles

A Delicate Balance Between Spin-Wave Mediated Weak Localization and Electron-Phonon Scattering in the Design of Zero Temperature Coefficient of Resistivity.

Zero thermal coefficients of resistivity (ZTCR) materials exhibit minimal changes in resistance with temperature variations, making them essential in modern advanced technologies. The current ZTCR materials, which are based on the resistivity saturation effect of heavy metals, tend to function at elevated temperatures because the mean free path approaches the lower limit of the semiclassical Boltzmann theory when the temperature is sufficiently high. ZTCR materials working at low-temperatures are difficult to achieve due to electron-phonon scattering, which results in increased resistivity according to Bloch's theory. In this work, the ZTCR behavior at low-temperatures is realized in pre-microstrained Mn3NiN. The delicate balance between the resistivity contribution from electron-phonon scattering and spin-wave mediated weak localization is well revealed. A remarkable temperature coefficient of resistivity (TCR) value as low as 1.9ppmK-1 (50K≤T≤200K) is obtained, which is significantly superior to the threshold value of ZTCR behavior and the application standard of commercial ZTCR materials. The demonstration provides a unique paradigm in the design of ZTCR materials through the contraction effects of two opposite conductance mechanisms with positive and negative thermal coefficients of resistivity.

Effect of processing on the stability and electrical properties of pressureless sintered graphene oxide–alumina composites

This paper explores the processing of an alumina matrix composite with a percolating network of graphene oxide (GPO), which exhibits a moderate electric resistivity and a near zero temperature coefficient of resistance. Different formulations of GPO–alumina composites were processed using a water–base blending, and, the pellets were densified by pressureless sintering under Argon flow. Electrical conduction at room temperature was achieved in the 2 wt % GPO–alumina composite sintered at 1400 °C, and, the 3 wt % GPO–alumina composites sintered at 1400, 1550 and 1700 °C. An investigation of the degradation of electrical conductivity was used to identify potential stable operating regimes in which these materials could be used as heaters. Thermogravimetric analysis using the Ozawa–Flynn–Wall method, was used to determine the kinetic parameters of a 3 wt % GPO composite sintered at 1400 °C which, had an activation energy for GPO degradation of 195 ± 68 kJ/mol and, an estimated thermal lifetime of 8.7 ± 0.8 years for a conversion of 0.5 wt % (failure criterion) at an application temperature of 340 °C.

Low percolation conductive graphite flakes-filled poly(urethane-imide) composites with high thermal stability via imidization self-foaming structure

In the study, the conductive graphite flakes filled poly(urethane-imide) composites (PUI/GFs) with high performance were constructed by the thermal imidization self-foaming reaction. It was found that the foaming action could promote the redistribution of GFs during curing process and the formation of stable linear conductive pathways. The percolation threshold of PUI/GFs composites was lowered from 1.26 wt% (2000 mesh GFs) or 0.86 wt% (1000 mesh GFs) to 0.79 wt% (500 mesh GFs), which were relatively low percolation thresholds for polymer/GFs composites so far. When the content of 500 mesh GFs was 4.0 wt%, the electrical conductivity of the composite was as high as 3.96 × 10−1 S/m. Also, a poly(urethane-imide) (PUI) matrix with excellent thermal stability (Td10%: 334.97 °C) and mechanical properties (elongation at break: 324.52%, tensile strength: 15.88 MPa) was obtained by introducing the rigid aromatic heterocycle into the polyurethane (PU) hard segments. Moreover, the zero temperature coefficient of resistivity for the composites was observed at the temperature range from 30 °C to 200 °C. Consequently, PUI/GFs composites may provide the novel strategy for considerable conductive materials with high thermal stability in electrical conductivity.

High-performance electrical properties of La-based perovskite ceramics for the functional phase of thick film resistors

In order to explore an economical functional phase alternative material for thick film resistors, the crystal structure, microstructure, and electrical properties of (1-x)La0.5Sr0.5Co0.96Ni0.04O3-δ + xLaCo0.4Ni0.58Zn0.02O3 (x = 0.0–1.0) composite ceramics were studied through solid-state reaction experiments. The composite ceramics were characterized by x–ray diffraction, scanning electron microscopy, energy dispersive x–ray spectroscopy, X-ray photoelectron spectroscopy, and DC four–probe method. Results suggested that the main phases of La0.5Sr0.5Co0.96Ni0.04O3-δ and LaCo0.4Ni0.58Zn0.02O3 were formed, along with a small part of impurity phases. The addition of LaCo0.4Ni0.58Zn0.02O3 to La0.5Sr0.5Co0.96Ni0.04O3-δ decreased the electrical conductivity and changed the temperature coefficient of resistance from positive to negative. Zero temperature coefficient of resistance could be achieved around 0.6 < x < 0.8 and relatively low absolute temperature coefficient of resistance values could be obtained for the samples of 0.4 ≤ x ≤ 0.8. The ceramic of 0.6La0.5Sr0.5Co0.96Ni0.04O3-δ + 0.4LaCo0.4Ni0.58Zn0.02O3 showed the optimal performances of conductivity = 1923 S/cm, temperature coefficient of resistance = 379.54 ppm/°C, and relative density = 95.05%.

Zero temperature coefficient of resistance in back-end-of-the-line compatible titanium aluminum nitride films by atomic layer deposition

Thin film resistors with near-zero temperature coefficient of resistance (TCR) are key passive elements in analog integrated circuits (ICs). State-of-the-art near-zero TCR technology is based on sputtered compounds of Si, Cr, B, and C, which require annealing at temperatures higher than 500 °C, making it incompatible with back-end-of-the-line (BEOL) processes. We report here that near-zero TCR resistors can be obtained by atomic layer deposition (ALD) of TiN-AlN nano-laminates at BEOL-compatible deposition temperature. The resistivity and the TCR can be tuned by varying the ratio between AlN (insulating) and TiN (metallic) in the TiXAl1−XN thin film. The TCR changes from positive to negative as the AlN content is increased, allowing for optimization to zero TCR. The ALD method provides ultimate control of the thickness, composition ratio, coverage, and uniformity. Microstructure analysis shows that the film consists of metallic TiN crystallites embedded in the semiconducting TiyAl1−yN amorphous matrix, suggesting that the electrical behavior is similar to that of SiCr-based compounds. These results pave the way toward BEOL-compatible near-zero TCR thin film resistors, which can significantly reduce capacitance and minimize design complexity of passive analog IC components.

Balancing Scattering Channels: A Panoscopic Approach toward Zero Temperature Coefficient of Resistance Using High-Entropy Alloys.

Designing alloys with an accurate temperature-independent electrical response over a wide temperature range, specifically a low temperature coefficient of resistance (TCR), remains a big challenge from a material design point of view. More than a century after their discovery, Constantan (Cu-Ni) and Manganin (Cu-Mn-Ni) alloys remain the top choice for strain gauge applications and high-quality resistors up to 473-573 K. Here, an average TCR is demonstrated that is up to ≈800 times smaller in the temperature range 5-300 K and >800 times smaller than for any of these standard materials over a wide temperature range (5 K < T < 1200 K). This is achieved for selected compositions of Alx CoCrFeNi high-entropy alloys (HEAs), for which a strong correlation of the ultralow TCR is established with the underlying microstructure and its local composition. The exceptionally low electron-phonon coupling expected in these HEAs is crucial for developing novel devices, e.g., hot-electron detectors, high-Q resonant antennas, and materials in gravitational wave detectors.

Zero temperature coefficient of resistance of the electrical-breakdown path in ultrathin hafnia

The recent widespread attention on the use of the non-volatile resistance switching property of a microscopic oxide region after electrical breakdown for memory applications has prompted basic interest in the conduction properties of the breakdown region. Here, we report an interesting crossover from a negative to a positive temperature dependence of the resistance of a breakdown region in ultrathin hafnia as the applied voltage is increased. As a consequence, a near-zero temperature coefficient of resistance is obtained at the crossover voltage. The behavior may be modeled by (1) a tunneling-limited transport involving two farthest-spaced defects along the conduction path at low voltage and (2) a subsequent transition to a scattering-limited transport after the barrier is overcome by a larger applied voltage.

Near zero temperature coefficient of resistance in Ti:Si:O thin films deposited by magnetron co-sputtering

Thin films of titanium/silicon/oxygen (Ti:Si:O) deposited by sputtering were evaluated as thin film resistors and the resulting resistance and temperature coefficient of resistance (TCR) was studied. The films were deposited in an Argon atmosphere at room temperature with 1% oxygen and their electrical properties evaluated before and after forming gas (5% H2: 95% N2) annealing at 325 and 450 °C for 1 h. The physical structure was characterized by x-ray diffraction (XRD), elemental composition and depth profile by Rutherford backscattering (RBS), and film composition by x-ray photoelectron spectroscopy (XPS). Carrier mobility, type and concentration were evaluated by Hall effect measurements. Thin films with a Ti:Si ratio of 1.6 exhibited a near zero TCR (−405 ppm °C−1) and sheet resistance (Rsh) at 25 °C of 1 kOhm sq−1.

Magnetic/structural phase diagram and zero temperature coefficient of resistivity in GaCFe3−xCox (0 ≤ x ≤ 3.0)

Magnetic/structural phase diagram of GaCFe3−xCox (0 ≤ x ≤ 3.0) were investigated systematically. It was found that the antiperovskite phase collapses at x = 0.90 and recovers again at x = 2.3 with Co doping. Along with this transformation, the ferromagnetic state in GaCFe3 is suppressed and replaced by the reentrant spin-glass state (2.3 ≤ x ≤ 2.6) or enhanced magnetic fluctuations (2.7 ≤ x ≤ 3.0). Ac susceptibility and magnetic relaxation were adopted to validate this spin-glass state for x = 2.5. It indicates that the contractive lattice as well as the resultant enhanced magnetic couplings may be an important origin of the collapsed antiperovskite structure. Zero temperature coefficient of resistivity (TCR) was achieved by Co-doping where the sign of TCR changes from positive to negative across the room temperature. The optimized TCR ∼ 0.0346 ppm/K spanning 110 K are three orders of magnitude smaller than those of CuNMn3 or GaCFe3. The physical mechanism was discussed.

Smart conducting polymer composites having zero temperature coefficient of resistance

Zero temperature coefficient of resistance (TCR) is essential for the precise control of temperature in heating element and sensor applications. Many studies have focused on developing zero-TCR systems with inorganic compounds; however, very few have dealt with developing zero-TCR systems with polymeric materials. Composite systems with a polymer matrix and a conducting filler show either a negative (NTC) or a positive temperature coefficient (PTC) of resistance, depending on several factors, e.g., the polymer nature and the filler shape. In this study, we developed a hybrid conducting zero-TCR composite having self-heating properties for thermal stability and reliable temperature control. The bi-layer composites consisted of a carbon nanotube (CNT)-based layer having an NTC of resistance and a carbon black (CB)-based layer having a PTC of resistance which was in direct contact with electrodes to stabilize the electrical resistance change during electric Joule heating. The composite showed nearly constant resistance values with less than 2% deviation of the normalized resistance until 200 °C. The CB layer worked both as a buffer and as a distributor layer against the current flow from an applied voltage. This behavior, which was confirmed both experimentally and theoretically, has been rarely reported for polymer-based composite systems.

Zero temperature coefficient of resistivity induced by photovoltaic effect in Y Ba2Cu3O6.96 ceramics

I-V characteristics of YBCO-Ag system under blue laser (λ = 450 nm) illumination were studied from 100 to 300 K and obvious photovoltaic effects were observed. All the I-V curves in the temperature range intersect at a point in the first quadrant while the laser points to the cathode electrode, indicating a zero temperature coefficient of resistivity. This implies that the outputting voltage keeps constant in a broad temperature range when a critical bias current is assigned. The intersection points of different laser intensities fall in a straight line, the slope of which (Rc) is independent of temperature and laser intensity.

Fabrication of a Hybrid Carbon-Based Composite for Flexible Heating Element With a Zero Temperature Coefficient of Resistance

We report on a hybrid carbon-based composite for zero temperature coefficient of resistance (TCR) heating element, forming edge-island type composite comprised of carbon nanotubes (CNTs) and carbon blacks (CBs) with a polydimethylsiloxane. The island-shaped CB composite is placed between a copper connection electrode and the CNT composite, acting as both a buffer and distribution layer against current flow for a zero TCR. The degree of control over this zero TCR was characterized by examining the thickness ratio between the CNT and CB layers. The optimized edge-island composite structure showed a constant normalized resistance (with <;3% deviation) to 200 °C with a rapid heating property. This edge-island composite structure could be widely used for heat-related or sensor applications, solving safety, and accuracy issues.

Tunable room-temperature zero temperature coefficient of resistivity in antiperovskite compounds Ga1−xCFe3 and Ga1−yAlyCFe3

The effects of the Ga content and the substitution of Al for Ga on the temperature coefficient of resistivity (TCR) of antiperovskite GaCFe3 have been investigated systematically. Our results indicate the value of TCR and its temperature range can be tuned by altering chemical compositions. With decreasing the Ga content in Ga1−xCFe3 or increasing Al dopant in Ga1−yAlyCFe3, the sign of TCR changes from positive to negative and room-temperature zero TCR material can be achieved. Typically, the optimized TCR values are about −5.72 ppm/K(265–315 K) and −14.68 ppm/K(280–320 K) for Ga0.95CFe3 and Ga0.85Al0.15CFe3, respectively. The possible mechanisms for the observed low TCR are discussed.

CVD silicon carbide electric heaters

This paper describes the growth of tubular polycrystalline 3C-SiC samples by chemical vapor deposition (CVD). The use of propionitrile as a precursor for nitrogen doping ensures the growth of polycrystalline 3C-SiC layers with a 1000°C resistivity of 0.1–0.2 Ω cm and zero temperature coefficient of resistance. Such 3C-SiC tubes can be used as silicon carbide electric heaters.

Near zero temperature coefficient of resistivity in antiperovskite Mn3Ni1−xCuxN

The near zero temperature coefficient of resistivity (NZ-TCR) in Mn-based antiperovskite Mn3Ni1−xCuxN is reported. The temperature range of NZ-TCR is controllable by changing Cu content. Further, the TCR value of 0.09 ppm K−1 was obtained in Mn3Ni0.5Cu0.5N over a broad temperature range around room temperature. The anomalous resistivity change of Mn3Ni1−xCuxN from metal-like to NZ-TCR behavioris apparently due to a magnetic transition. The possible reason for the formation of NZ-TCR is interpreted on the basis of spin-disorder scattering.

Tunable temperature coefficient of resistivity in C- and Co-doped CuNMn 3

Antiperovskite intermetallic compounds, including CuN 1− x C x Mn 3 and CuNMn 3− y Co y , have been synthesized. The temperature coefficient of resistivity (TCR) decreases with increasing dopant and changes the sign from positive to negative. For x = 0.05, TCR is only 1.29 ppm K −1 between 240 and 320 K. Zero TCR will appear at certain doping levels (0.05 ⩽ x ⩽ 0.07 or 0.2 ⩽ y ⩽ 0.3), indicating great commercial prospects. The possible reason for zero TCR is analyzed based on the optimization of the electronic structure and electron–phonon scattering.

Controlling temperature coefficient of resistivity in La 1− xSr xMnO 3 ceramics

We propose La 1− x Sr x MnO 3 as a new lead-free and ruthenium-free conductive oxide used for thick film resistors. The temperature coefficient of resistivity ( TCR) of the La 1− x Sr x MnO 3 was controlled systematically by changing the composition x. The TCR behavior depended on the change of the crystal symmetries and the average valence of Mn ions. The highest value of 9356 ppm/°C was obtained at the x = 0.35. Zero TCR was realized around 0.200 < x < 0.225 and 0.45 < x < 0.50, where the critical x values were related to the characteristic change from Mott-insulator to metallic behavior. The systematical controlling TCR and the zero TCR are the first to be demonstrated for conductive oxide.

Ti/Ni(80%)Cr(20%) Thin-Film Resistor With a Nearly Zero Temperature Coefficient of Resistance for Integration in a Standard CMOS Process

A thin-film resistor out of Ni(80%)Cr(20%) for integration in a standard complementary metal-oxide-semiconductor process with a temperature coefficient of resistance (TCR) below 10 ppm/K was realized by applying a thin Ti layer underneath. The Ti-layer thickness and the temperature and duration of furnace annealing after deposition were optimized in different experiments. The combination of 5-nm Ti + 10-nm NiCr and a 30-min heat treatment at 350degC in a forming gas ambient was found to yield a sheet resistance of about 140 Omega/sq and a TCR of below 10 ppm/K. The long-term drift of the sheet resistance after 1000 h at 200degC was about 0.3%. A transmission electron microscopy analysis was conducted to investigate the structure of the film and a possible change during annealing. An Auger analysis was conducted for film surface analysis.

Tantalum nitride/copper nanocomposite with zero temperature coefficient of resistance

We report the design of a new nanocomposite exhibiting a zero temperature coefficient of resistivity, which are composed of tantalum nitride and copper nanoparticles. With the increase in copper content, the temperature coefficient of resistivity of the TaN–Cu nanocomposites changed from negative to positive values and achieved zero value at 37.5 at.% copper. The micrograph showed that the nanocomposites can be described as nano/nano type (two nanophases) ceramic.

Study of pre-localized graphite/polyvinyl chloride electroconductive composites for sensors

Electroconductive composites were prepared by compression moulding of graphite-coated polyvinyl chloride (PVC) below and above the glass transition temperature (Tg). Compaction below Tg shows notable effect on percolation concentration and room temperature resistivity. The resistivity as a function of composition and temperature has been studied. For higher compositions zero temperature coefficient of resistivity (ZTCR) is observed. The results of electron microscopy studies indicate that graphite is distributed between the interparticle spaces of PVC resin, forming a network of graphite channels. The thickness of channels increases with the increase of graphite content. The methods of preparation along with the processing parameters significantly affect the resistivity of the composites. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)