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1.
Pressure and pressureless electrical contacts were evaluated by measuring the contact electrical resistivity between copper
mating surfaces. Pressure electrical contacts with a contact resistivity of 2×10−5 Ω·cm2 have been attained using a carbon black paste of a thickness of less than 25 μm as the interface material. In contrast, a
pressureless contact with silver paint as the interface material exhibits a higher resistivity of 3×10−5 Ω·cm2 or above. A pressureless contact with colloidal graphite as the interface material exhibits the same high contact resistivity
(1×10−4 Ω·cm2) as a pressure contact without any interface material. On the other hand, pressureless contacts involving solder and silver
epoxy exhibit lower contact resistivity than carbon black pressure contacts. 相似文献
2.
An air-fireable, glass-free, electrically conductive thick-film material (96.6% Ag, 1.38% Cu, 0.28% Al, 0.35% Ti, and 1.39%
Sn by weight) and a conventional glass-containing, electrically conductive thick-film materials (96.6% Ag and 3.4% glass frit
by weight), both on alumina substrates, were studied by electrical, mechanical, thermal, and microscopic methods. The volume
electrical resistivity of the glass-free thick film (2.5×10−6 Ω·cm, 30-μm thick) is lower than that of the glass-containing thick film (3.9×10−6 Ω·cm, 19-μm thick), with each film processed at its optimum firing temperature. The optimum firing temperature is 930°C and
850°C for glass-free and glass-containing thick films, respectively, as indicated by the criteria of low resistivity and high
scratch resistance. The glass-free thick film has a higher scratch resistance than the glass-containing thick film, both fired
at their respective optimum temperatures, suggesting that the former has higher bond strength to the alumina substrate. The
formation process of the glass-free and glass-containing thick films is similar. The process involves solid-state diffusion
of silver, which results in a silver network and grain boundaries. However, the sintering of silver particulates in the glass-containing
thick film is enhanced by the viscous flow of glass. 相似文献
3.
Electrically nonconductive thermal pastes have been attained using carbon (carbon black or graphite) as the conductive component
and ceramic (fumed alumina or exfoliated clay) as the nonconductive component. For graphite particles (5 μm), both clay and alumina are effective in breaking up the electrical connectivity, resulting in pastes with electrical resistivity
up to 1013Ω·cm and thermal contact conductance (between copper surfaces of roughness 15 μm) up to 9 × 104 W/m2·°C. For carbon black (30 nm), clay is more effective than alumina, providing a paste with resistivity 1011 Ω·cm and thermal contact conductance 7 × 104 W/m2·°C. Carbon black increases the thermal stability, whereas either graphite or alumina decreases the thermal stability. The
antioxidation effect of carbon black is further increased by the presence of clay up to 1.5 vol.%. The addition of clay (up
to 0.6 vol.%) or alumina (up to 2.5 vol.%) to graphite paste enhances the thermal stability. 相似文献
4.
Silver particle (3 μm) carbon-matrix composites in the form of thick films (around 100 μm thick) on alumina, as prepared from pastes comprising silver and mesophase pitch particles (14 μm), have been attained. The films on alumina were fired at 650°C in nitrogen to convert pitch to carbon. The volume electrical
resistivity attained ranged from 10−5 Ω cm to 104 Ω cm, depending on the silver volume fraction. The percolation threshold was 12 vol% silver. 相似文献
5.
Chia-Ken Leong Yasuhiro Aoyagi D. D. L. Chung 《Journal of Electronic Materials》2005,34(10):1336-1341
This paper addresses thermal interface materials for thermal conduction of excess heat for microelectronic applications. Carbon
black (30 nm) thixotropic paste based on polyol ethers is comparable to carbon black fluidic paste based on polyethylene glycol
(PEG) in its effectiveness as a thermal paste, and in its dependence on pressure history. Prior pressure (up to 0.69 MPa)
application is helpful. The optimum carbon black content is 2.4 vol.% for the thixotropic paste. The thermal contact conductance
across copper surfaces is 30 × 104 and 11 × 104 W/m2-°C for surface roughness of 0.05 μm and 15 μm, respectively. The volume electrical resistivity is 3 × 103 Ω-cm. Boron nitride (BN) (5–11 μm) and graphite (5 μm) thixotropic pastes are less effective than carbon black thixotropic
paste by up to 70% and 25%, respectively, in thermal contact conductance, due to low conformability. 相似文献
6.
We report the effect of steam oxidation at 875° C on the electrical resistivity, crystalline quality (measured by ion channeling),
and Al concentration (measured by secondary ion mass spectrometry) in 0.25 μm thick, Si-implanted and recrystallized, Si-on-sapphire
films. After a deep Si implantation (180 keV, 1.4×l015 Si/cm2) at room temperature, and solid-phase epitaxial regrowth from the non-amorphized, 0.03 μm thick surface region, the initially
undoped SOS films become doped p-type, and their resistivity decreases from (1−5)xl014 ficm to 0.5 Ωcm. The doping is due to electrically active Al, released from the A12O3 by the Si implantation, and present in the recrystallized films at a concentration of ≃2×l016 Al/cm3 . After a 75 min steam oxidation at 875 °C, which consumes 0.06 Μm of Si, the resistivity of the recrystallized films increases
to over 40 Ωcm, but the Al concentration is unchanged. The oxidation also uncovers higher quality material below the non-recrystallized
surface layer. A semi-quantitative model is proposed to explain the electrical data, based on the diffusion of oxygen from
the Si/SiO2 interface into the SOS film during oxidation, and the formation of Al-O-Si neutral complexes. Data on the stability of the
high-resistivity films against high-temperature annealing or re-amorphization and annealing is given. 相似文献
7.
Low-temperature air-fireable glass-free metallic thick-film electrical conductor materials were developed for interconnections
in electronic packaging. The thick film with composition (by weight) 96.60%Ag, 1.38%Cu, 0.28%Al, 0.35%Ti, and 1.39%Sn used
Ti−Al as the active binder. After firing in air at 500 C it exhibited low electrical resistivity (6.2×10−6Ω-cm), good scratch resistance and strong bonding with the alumina substrate, with no pinholes. The firing caused complete
melting of the particles in the film. Firing in argon rather than air degraded both electrical and bonding properties, due
to the absence of oxygen, which helped to burn out the vehicle. The use of Ti rather than Ti−Al as the active binder resulted
in holes in the thick film due to incomplete melting of the Ti-rich particles and also resulted in poor scratch resistance
and weaker bonding to the substrate. Tin in the composition was important for promoting melting and protecting the active
particles from oxidation during firing. 相似文献
8.
Manganese-doped zinc oxide (Mn-doped ZnO) thin films were prepared using chemical bath deposition (CBD), and the impacts of
the manganese dopant concentration on the structure, electrical resistivity, optical transmission, and magnetic properties
were investigated using x-ray diffractometry, Hall-effect measurements, ultraviolet–visible–near-infrared (UV–Vis–IR) spectrophotometry,
and vibrating sample magnetometry (VSM), respectively. The concentration of the manganese dopant in the ZnO thin film critically
impacted the resulting properties, and the 4.0 at.% Mn-doped ZnO film had a resistivity of 5.8 × 10−2 Ωcm, transmittance of 75.6% in the visible light range, and bandgap of 3.30 eV when the film was annealed at 600°C in an
Ar + H2 atmosphere. Annealing the film could enhance its magnetic properties such that the film had a saturation magnetization of
21.0 emu/cm3 and a coercivity of 45.7 Oe after annealing at 600°C. Because of these electrical, optical, and magnetic properties, Mn-doped
thin films are promising for use in spintronic devices. 相似文献
9.
In this study, Ga-doped ZnO (GZO) transparent conducting thin films were prepared by pulsed direct-current magnetron sputtering,
providing good transparency and relatively low resistivity. The films were further etched in different aqueous solutions,
0.5% HCl, 5% oxalic acid, and 33% KOH, to modify their light-scattering properties. The results showed that film textured
by 0.5% HClaq. for 30 s had total optical transparency of T
total = 77.4% and haze value of H
T = 0.16, with electrical resistivity of ρ = 4.9 × 10−4 Ω-cm. For film textured in 5% oxalic acid solution for 75 s, the lowest electrical resistivity of 4.3 × 10−4 Ω-cm was achieved with relatively high total optical transparency of T
total = 75.1%, as well as a more ideal haze value of H
T = 0.3. Film textured in 33% KOH solution for 135 s (500 nm thickness) had optimal electrical conductivity of 5.1 × 10−4 Ω-cm with T
total = 75.6%, and a relatively low haze value of H
T = 0.12. GZO film textured with an agitated etch of 5% oxalic acid at 300 K would be the most suitable candidate for photovoltaic
applications due to its high transparency and good electrical conducting properties. 相似文献
10.
Development of rf sputtered,Cu-doped ZnTe for use as a contact interface layer to p-CdTe 总被引:5,自引:0,他引:5
T. A. Gessert A. R. Mason R. C. Reedy R. Matson T. J. Coutts P. Sheldon 《Journal of Electronic Materials》1995,24(10):1443-1449
Cu-doped ZnTe films deposited by rf-magnetron sputtering have been analyzed with the intention to use this material as a contact
interface in CdS/CdTe thin-film photovoltaic solar-cell devices. It is observed that unless careful attention is made to the
pre-deposition conditioning of the ZnTe target, the electrical resistivity of thin films (∼70 nm) will be significantly higher
than that measured on thicker films (∼1.0 μm). It is determined that N contamination of the target during substrate loading
is likely responsible for the increased film resistivity. The effect of film composition on the electrical properties is further
studied by analyzing films sputtered from targets containing various Cu concentrations. It is determined that, for targets
fabricated from stoichiometric ZnTe and metallic Cu, the extent of Zn deficiency in the film is dependent on both sputtering
conditions and the amount of metallic Cu in the target. It is observed that the carrier concentration of the film reaches
a maximum value of ∼3 × 1020 cm−3 when the concentrations of Te and (Zn+Cu) are nearly equal. For the conditions used, this optimum film stoichiometry results
when the concentration of metallic Cu in the target is ≈6 at.%. 相似文献
11.
Wei-Hsiang Luo Ting-Kan Tsai Jen-Chieh Yang Wei-Ming Hsieh Chia-His Hsu Jau-Shiung Fang 《Journal of Electronic Materials》2009,38(11):2264-2269
Highly conductive and transparent zinc oxide thin films were prepared on cleaned Corning Eagle2000 glass substrates by chemical bath deposition (CBD) using Zn(NO3)2 and (CH3)2NHBH3; the effects of annealing on the structural, electrical and optical properties were investigated. The electrical properties
of the film were greatly affected by annealing. Structural characterization was performed by x-ray diffraction and field emission
scanning electron micro- scopy. The thin film had a low resistivity of 2.9 × 10−2 Ω cm, an average transmittance of 81.2%, and a bandgap of 3.23 eV (which is in the visible range) when the film was annealed
at 600°C in Ar + H2. The results demonstrated that a low-resistivity and high-transmittance zinc oxide film can be prepared by CBD, which makes
the process readily applicable for a roll-to-roll process. 相似文献
12.
E. Broitman N. Hellgren J. Neidhardt I. Brunell L. Hultman 《Journal of Electronic Materials》2002,31(9):L11-L15
The influence of hydrogen content and ambient humidity on the electrical properties of carbon nitride (CNx) films deposited by reactive magnetron sputtering from a graphite target in Ar discharges mixed with N2 and H2 at a substrate temperature of 350°C have been investigated. Carbon films deposited in pure Ar exhibit a dark resistivity
at room temperature of ∼4 × 10−2 Ωcm, while the resistivity is one order of magnitude lower for CN0.25 films deposited in pure N2, due to their denser morphology. The increasing H2 fraction in the discharge gas leads to an increased resistivity for all gas mixtures. This is most pronounced for the nitrogen-free
films deposited in an Ar/H2 mixture, where the resistivity increases by over four orders of magnitude. This can be related to a decreased electron mobility
as H inhibits the formation of double bonds. After exposure to air, the resistivity increases with time through two different
diffusion regimes. The measured electrical properties of the films are related to the apparent film microstructure, bonding
nature, and ambient humidity. 相似文献
13.
Resilient metal spring silicone-matrix conducting composites for separable interconnections in electronics were fabricated
by the impregnation of silicone into a preform comprising randomly oriented C-shaped Cu-Be springs and a small proportion
of Sn-Pb solder, which served to connect the springs at some of their intersections. Composites containing 6.1-9.8 vol.% total
filler exhibited volume electrical resistivity 0.5-1.0 mΩ.cm and contact resistivity (with copper) 11-17 mΩ.cm2. A compressive stress of about 30 kPa was needed for the low contact resistivity to be reached. The volume 17-26% and the
contact resistivity increased by 5% after heating in air at 130-150°C for seven days. Composites containing <9 vol.% total
filler showed no stress relaxation for seven days at 6.0% strain. 相似文献
14.
The electrical behavior during annealing of copper films with a nominal concentration of 2 at.% boron has been investigated.
The evolution of the resistivity of the film was monitored using an in situ technique, in which the film was rampannealed
at constant ramp rates. At temperature of 150–200°C, the resistivity of the Cu(B) undergoes a first drop. This is followed
by one or two such drops in resistivity, so that after completion of a ramp-anneal from 50°C to 750°C, the room temperature
resistivity decreases from the initial value of 13 μΩ cm to 2.1 μΩcm, close to that of bulk copper. Isothermal annealing of
the film also leads to substantial decreases in resistivity, from 13 μΩcm to 3 μΩ cm after annealing at 350°C for 8 h and
to 2.5 μΩ cm at 400°C for 4 h. These results show that a dramatic reduction in resistivity of Cu(B) alloys takes place at
temperatures below 400°C, suggesting possible applications for silicon device interconnections. 相似文献
15.
Jianguo Liu Baling Huang Xiangyou Li Ping Li Xiaoyan Zeng 《Journal of Electronic Materials》2010,39(12):2702-2710
Magnetic silver-coated ferrite nanoparticles with 39.8% weight gain (relative to ferrite nanopowder coated by a silver layer)
were synthesized by electroless deposition of silver on ferrite nanopowder. The mechanism of the electroless deposition was
explored in terms of pretreatment, sensitization, activation, and the reduction of silver–ammonia complexes. Experiments showed
that the optimal deposition conditions were a temperature of 50°C, pH value of 10 to 12, duration of 65 min with ethanol plus
polyethylene glycol as additives, and ultrasonic vibration as a method of dispersing the nanoparticles. From transmission
electron microscopy (TEM) images, it was observed that as-synthesized nanoparticles had a core–shell structure with a particle
size of 35 nm to 90 nm and a shell thickness of 5 nm to 20 nm. X-ray diffraction (XRD) analysis confirmed that only ferrite
and metallic silver were present in the product. Electrical resistance and magnetic hysteresis measurements demonstrated that
the nanoparticles were both electrically conductive (volume electrical resistivity on the order of 10−4 Ω cm to 10−3 Ω cm when compressed to pressure of 2 × 10 6 Pa) and possessed ferrimagnetic properties. After a thick-film paste, obtained with the nanoparticles as the functional phase,
was directly written and sintered, scanning electron microscopy (SEM) analysis and electrical resistance measurements of conductive
lines in the acquired array pattern showed that an electrically conductive network with some defects and cavities was formed,
with a volume electrical resistivity of 1 × 10−4 Ω cm to 1 × 10−3 Ω cm. 相似文献
16.
We have explored the electrical conductivity of thick films made from silver methylcarbamate paste using metallic silver as the electrically conductive phase. The paste was composed of 30 wt.% to 90 wt.% organic vehicle and 10 wt.% to 70 wt.% functional phase precursor (silver methylcarbamate). After the paste was sintered, films with thickness of 4.50 μm to 12.70 μm were obtained, in which the elemental percentage of silver varied from about 5 wt.% to above 99 wt.%. Experiments showed that both the electrical conductivity and the elemental percentage were mainly affected by the initial silver content in the paste and the parameters of the sintering process. For given sintering conditions, higher initial silver content led to higher elemental percentage of silver, improving the electrical conductivity of the thick film. The conditions of the sintering process had a significant influence on the evaporation and decomposition rates of the paste components, the elemental percentage of silver, and the microstructure of the thick film. Higher temperatures, longer times, lower heating rates, and more oxygen-rich sintering atmospheres were found to accelerate the evaporation and decomposition and increase the elemental percentage of silver, both of which served to enhance the electrical conductivity. For initial silver contents less than about 10 wt.%, the lowest electrical resistivity of the thick film only reached the order of 10?4 Ω cm, irrespective of the sintering conditions. For contents between 10 wt.% and 25 wt.%, it was possible to attain lowest resistivity values on the order of 10?5 Ω cm. Above 25 wt.%, the lowest resistivity could reach 10?6 Ω cm, comparable to that of bulk silver. 相似文献
17.
Y. He J. Ramdani N. A. El-Masry D. C. Look S. M. Bedair 《Journal of Electronic Materials》1993,22(12):1481-1485
Low-temperature (LT) growth of In0.47Ga0.53P was carried out in the temperature range from 200 to 260°C by gas source molecular beam epitaxy using solid Ga and In and
precracked PH3. The Hall measurements of the as-grown film showed a resistivity of ∼106 Ω-cm at room temperature whereas the annealed film (at 600°C for 1 h) had at least three orders of magnitude higher resistivity.
The Hall measurements, also, indicated activation energies of ∼0.5 and 0.8 eV for the asgrown and annealed samples, respectively.
Double-crystal x-ray diffraction showed that the LT-InGaP films had ∼47% In composition. The angular separation, Δθ, between
the GaAs substrate and the as-grown LT-InGaP film on (004) reflection was increased by 20 arc-s after annealing. In order
to better understand the annealing effect, a LT-InGaP film was grown on an InGaP film grown at 480°C. While annealing did
not have any effect on the HT-InGaP peak position, the LT-InGaP peak was shifted toward the HT-InGaP peak, indicating a decrease
in the LT-InGaP lattice parameter. Cross-sectional transmission electron microscopy indicates the presence of phase separation
in LT-InGaP films, manifested in the form of a “precipitate-like” microstructure. The analytical scanning transmission electron
microscopy analysis of the LT-InGaP film revealed a group-V nonstoichiometric deviation of ∼0.5 at.% P. To our knowledge,
this is the first report about the growth and characterization of LT-InGaP films. 相似文献
18.
Jung-Hsiung Shen Sung-Wei Yeh Hsing-Lu Huang Dershin Gan New-Jin Ho 《Journal of Electronic Materials》2010,39(5):612-618
Low-temperature growth of undoped ZnO films with high transparency and low electrical resistance was performed by ion beam
sputtering. After systematic testing, resistivity as low as 2.95 × 10−3 Ω cm was obtained at a substrate temperature of 150°C, ion source voltage of 850 V, and ion beam current of 30 mA. The transmittance
of the ZnO films was in the range of 85% to 90%. Hall measurements showed that a high mobility of 21.41 cm2/Vs was obtained for films less than 200 nm thick. The related microstructures and physical properties were measured and are
discussed. 相似文献
19.
Samples of composites of graphene with indium or indium-gallium alloy as the matrix were prepared by a process of spreading
exfoliated graphene oxide on the foils, repeatedly folding and rolling. The foils were intermittently annealed and the process
repeated by addition of more graphene oxide. Indium flux was used to remove any indium or gallium oxide. The samples were
characterized by x-ray diffraction, and optical and scanning electron microscopy (SEM). Electrical resistivity and temperature
coefficient of resistance (TCR) were measured using a four-probe method in the temperature range of 260 K to 340 K, and the
results were used to determine the volume fraction of graphene from effective mean-field analysis. The volume fraction of
graphene remained between 0.11 and 0.14 in samples of In with graphene and between 0.12 and 0.13 in samples of In-Ga with
graphene. The results indicate that the electrical resistivity and the TCR of the composite were reduced by the addition of
graphene. The resistivity of graphene remained between 1.19 × 10−6 ohm cm and 1.87 × 10−6 ohm cm in all samples and was thus almost independent of the matrix composition. The electrical resistivity of graphene was
found to be an order of magnitude smaller than that of indium or the indium-gallium alloy. 相似文献
20.
Q. Jiang A. W. Brinkman B. J. Cantwell J. T. Mullins Fabrice Dierre A. Basu P. Veeramani P. Sellin 《Journal of Electronic Materials》2009,38(8):1548-1553
This paper reports on a detailed study of the development of the close space sublimation method, which has been widely used
in the preparation of polycrystalline CdTe/CdS solar cells, as an epitaxial method for the growth of thick CdTe single crystal
films over 200 μm on GaAs and Ge substrates for high-energy radiation detectors. The resulting microscopic growth phenomena in the process
are also discussed in this paper. High-quality single crystalline CdTe thick films were prepared with x-ray rocking curves
full width at half maximum (FWHM) values, which were ∼100 arcsec on Ge substrates and 300 arcsec on GaAs substrates. The quality
of thick films on Ge(100) showed a substantial improvement with nucleation in a Te-rich growth environment. No Te inclusions
in the CdTe films grown on GaAs(211)B and Ge(100) were observed with IR transmission imaging. Photoluminescence of CdTe/Ge
shows a large reduction in the 1.44 eV defect energy bands compared with films grown on GaAs substrates. The film resistivity
is on the order of 1010 Ω cm, and the film displayed some sensitivity to alpha particles. 相似文献