共查询到20条相似文献,搜索用时 93 毫秒
1.
Alexander Klushin Alexander Golubov Werner Prusseit Hermann Kohlstedt 《Journal of Low Temperature Physics》1997,106(3-4):265-269
In order to optimize the series array performance of Y Ba2Cu3O7−x (YBCO) grain boundary shunted junctions, a method to determine and control the junction resistance Rs and Au/YBCO contact resistivity ρ
c
has been developed. 200 nm thick c-oriented YBCO films were grown by intermittent thermal coevaporation on bicrystal yttria-stabilized
zirconia substrates. A gold contact overlayer of thickness dn was deposited in situ. Normal junction resistances have been measured as a function of dn and shunt width w. It was shown that, in accordance with theoretical estimates, the junction shunt resistance is essentially
controlled by the c-axis Au/YBCO interface specific resistance and scales as
. The product ρ
c
ρ
n
≃ 3.10−14 Ω2
cm
3 was estimated from the experimental data, leading to ρ
c
≈ 10−8 Ωcm
2 for typical values of ρ
n
for gold thin films. 相似文献
2.
P. N. Vinod 《Journal of Materials Science: Materials in Electronics》2010,21(7):730-736
Porous silicon has been considered as a promising optoelectronic material for developing a variety of optoelectronic devices
and sensors. In the present study, the electrical properties and metallurgical process of the screen-printed Ag metallization
formed on the porous silicon surface of the silicon solar cell have been investigated. The contact structure consists of thick-film
Ag metal contact patterned on the top of the porous silicon surface. The sintering process consists of a rapid firing step
at 750–825 °C in air ambient. It results in the formation of a nearly perfect contact structure between the Ag metal and porous
silicon/p-Si structure that forms the top metalization for the screen-printed silicon solar cells. The SEM picture shows that
Ag metal firmly coalesces with the silicon surface with a relatively smooth interfacial morphology. This implies that high
temperature fire-through step has not introduced any signs of adverse effect of junction puncture or excessive Ag indiffusion,
etc. The three-point probe (TPP) method was applied to estimate the specific contact resistance, ρ
c (Ω-cm2) of the contact structure. The TPP measurement shows that contact structure has excellent ohmic properties with ρ
c = 1.2 × 10−6 Ω-cm2 when the metal contact sintered at 825 °C. This value of the specific contact resistance is almost three orders of magnitude
lower than the corresponding value of the ρ
c = 7.35 × 10−3 Ω-cm2 obtained for the contact structure sintered at 750 °C. This improvement in the specific contact resistance indicates that
with increase in the sintering temperature, the barrier properties of the contact structure at the interface of the Ag metal
and porous silicon structure improved which in turn results a lower specific contact resistance of the contact structure. 相似文献
3.
P. N. Vinod 《Journal of Materials Science: Materials in Electronics》2011,22(9):1248-1257
The specific contact resistance of the screen-printed Ag contacts in the silicon solar cells has been investigated by applying
two independent test methodologies such as three-point probe (TPP) and well-known transfer length model (TLM) test structure
respectively. This paper presents some comparative results obtained with these two measurement techniques for the screen-printed
Ag contacts formed on the porous silicon antireflection coating (ARC) in the crystalline silicon solar cells. The contact
structure consists of thick-film Ag metal contacts patterned on the top of the etched porous silicon surface. Five different
contact formation temperatures ranging from 725 to 825 °C for few minutes in air ambient followed by a short time annealing
step at about 450 °C in nitrogen ambient was applied to the test samples in order to study the specific contact resistance
of the screen-printed Ag metal contact structure. The specific contact resistance of the Ag metal contacts extracted based
on the TPP as well as TLM test methodologies has been compared and verified. It shows that the extraction procedure based
on the TPP method results in specific contact resistance, ρ
c
= 2.15 × 10−6 Ω-cm2 indicating that screen-printed Ag contacts has excellent ohmic properties whereas in the case of TLM method, the best value
of the specific contact resistance was found to be about ρ
c
= 8.34 × 10−5 Ω-cm2. These results indicate that the ρ
c
value extracted for the screen-printed Ag contacts by TPP method is one order of magnitude lower than that of the corresponding
value of the ρ
c
extracted by TLM method. The advantages and limitations of each of these techniques for quantitatively evaluating the specific
contact resistance of the screen-printed Ag contacts are also discussed. 相似文献
4.
P. N. Vinod 《Journal of Materials Science: Materials in Electronics》2009,20(10):1026-1032
The SEM and specific contact resistance measurements of the Ag metal contact formed by applying a fire-through process on
the shallow emitter region of the silicon solar cell have been investigated. The metal contact consists of screen-printed
Ag paste patterned on the silicon nitride (Si3N4) deposited over the n+-Si emitter region of the solar cell. The sintering step consists of a rapid firing step at 800 °C or above in air ambient.
This is followed by an annealing step at 450 °C in nitrogen ambient. It enables to drive the Ag metal paste onto the Si3N4 layer and facilitates the formation of an Ag metal/p-Si contact structure. It serves as the top metallization for the screen-printed
silicon solar cell. The SEM measurement shows that sintering of the Ag metal paste at 800 °C or above causes the Ag metal
to firmly coalesce with the underlying n+-Si surface. A thin layer of conductive glassy layer is also presents at the interface of the Ag metal and n+-Si surface. The electrical quality of the contact structure was characterized by measuring the specific contact resistance,
ρ
c
(in Ω-cm2) using the iteration technique based on the power loss calculation for the solar cell. It shows that best value of ρ
c
= 2.53 × 10−5 Ω-cm2 is estimated for the Ag metal contact sintered at temperature above 800 °C. This value of ρ
c
is two orders of magnitude lower than the typical value of ρ
c
= 3 × 10−3 Ω-cm2 reported previously for the Ag contacts of the solar cell. Such low value of ρ
c
for the Ag metal contacts indicates that fire-through process results in excellent ohmic properties. The plot of the ρ
c
versus impurity doping level (N
s
) shows that measured value of the ρ
c
follows a linear relationship with the N
s
as predicted by the theory for the heavily doped semiconductor surface. Hence, carrier injection across the Schottky barrier
height is quite appropriate to explain the observed ohmic properties of the Ag metal contacts on the n+-Si surface of the silicon solar cell.
相似文献
P. N. VinodEmail: |
5.
P. N. Vinod 《Journal of Materials Science: Materials in Electronics》2007,18(8):805-810
The establishment of a suitable contact formation methodology is a critical part of the technological development of any metal-to-semiconductor
contact structure. Many test structures and methodologies have been proposed to estimate the specific contact resistance (ρc) of the planar ohmic contacts formed on the heavily doped semiconductor surface. These test structures are usually processed
on the same wafer to monitor a particular process. In this study, new experimental procedure has been evolved to assess the
value of ρc of the screen-printed front silver (Ag) thick-film metal contact to the silicon surface. The essential feature of this methodology
is that it is an iteration technique based on the calculation of power loss associated with various resistive components of
the solar cell normalized to the unit cell area. Therefore, this method avoids the complexity of making the design of any
lay out of a standard contact resistance test structure like transmission line model (TLM) or Kelvin resistor, etc. It was
shown that value of specific contact resistance of the order of 1.0 × 10−5 Ω−cm
2 is measured for the Ag metal contacts formed on the n+ silicon surface. This value is much lower than the ρc data previously reported for the screen-printed Ag contacts. The sintering process of the front metal contact structure at
different furnace setting is carried out to understand the possible wet interaction and metal contact formation as a function
of the firing. Therefore, the study is further extended to study the peak firing temperature dependence of the ρc of screen-printed Ag metal contacts. It will help to assess the specific contact resistance of the ohmic contacts as a function
of firing temperature of sintering process.
相似文献
P. N. VinodEmail: |
6.
A recent experiment which measured the Nernst effect, the diamagnetic signal and the H
c2 field was interpreted as a support to the scenario which the pseudogap has the pair condensate without long-range phase coherence.
We present here calculations which qualitatively reproduces the onset of the Nernst signal temperature T
ν
(ρ) and T
c
(ρ) as function of the doping level ρ. Together with our previous calculations to the magnetization and H
c2, we conclude that the phase separation scenario supports also the new Nernst effect experiments.
This work has been partially supported by CAPES and CNPq. 相似文献
7.
V. N. Fuflyigin A. R. Kaul S. A. Pozigun L. Klippe G. Wahl 《Journal of Materials Science》1995,30(17):4431-4434
Thin films (0.7–0.8 μm) of Bi2Sr2CaCu2Ox were deposited by low-pressure metallorganic chemical vapour deposition with a single aerosol source. The influence of the
deposition parameters on the orientation of the films was studied. It was established that low deposition rate, high deposition
temperature and the presence of the liquid phase resulted in films with predominant c-orientation. 相似文献
8.
Undoped (IO) and Sn-doped In2O3 (ITO) films have been deposited on glass and polymer substrates by an advanced ion beam technologies including ion-assisted deposition (IAD), hybrid ion beam, ion beam sputter deposition (IBSD), and ion-assisted reaction (IAR). Physical and chemical properties of the oxide films and adhesion between films and substrates were improved significantly by these technologies. By using the IAD method, non-stoichiometry and microstructure of the films were controlled by changing assisted oxygen ion energy and arrival ratio of assisted oxygen ion to evaporated atoms. Relationships between structural and electrical properties in ITO films on glass substrates were intensively investigated by using the IBSD method with changing ion energy, reactive gas environment, and substrate temperature. Smooth-surface ITO films (Rrms ≤ 1 nm and Rp-v ≤ 10 nm) for organic light-emitting diodes were developed with a combination of deposition conditions with controlling microstructure of a seed layer on glass. IAR surface treatment enormously enhanced the adhesion of oxide films to polymer substrate. The different dependence of IO and ITO films' properties on the experimental parameters, such as ion energy and oxygen gas environment, will be intensively discussed. 相似文献
9.
D.Y. Kim 《Thin solid films》2008,516(11):3512-3516
Under certain conditions during ITO etching using CH4/H2/Ar inductively coupled plasmas, the etch rate selectivity of ITO to photoresist (PR) was infinitely high because the ITO films continued to be etched, but a net deposition of the α-C:H layer occurred on the top of the PR. Analyses of plasmas and etched ITO surfaces suggested that the continued consumption of the carbon and hydrogen in the deposited α-C:H layer by their chemical reaction with In and Sn atoms in the ITO resulting in the generation of volatile metal-organic etch products and by the ion-enhanced removal of the α-C:H layer presumably play important roles in determining the ITO etch rate and selectivity. 相似文献
10.
B. I. Belevtsev Yu. F. Komnik V. I. Odnokozov A. V. Fomin 《Journal of Low Temperature Physics》1984,54(5-6):587-605
Electrical and superconducting properties of indium films condensed in a H2 atmosphere (pressurep
H
2=6×10−6 to 1.4×10−4 Torr) onto a substrate cooled with liquid helium are investigated. As hydrogen content is increased, a continuous increase
in residual resistivity ρ* is observed, permitting systematic study of the resistance vs. temperature dependenceR(T) and the superconducting transition temperatureT
c on approaching the metal-insulator transition (MIT). With regard to ρ*, four regimes of conductivity can be observed: (1)
conductivity with a positive temperature resistance coefficient (TRC), (2) conductivity with a small, constant, negative TRC,
(3) conductivity under weak localization with ΔR (T) ∼ln T or
type corrections, (4) hopping conductivity.T
c rises continuously with ρ* and reaches its peak (∼5.2K) in the second regime. A further increase of ρ* leads to a decrease
ofT
c and complete suppression of superconductivity. The experimental dependenceR(T) is compared with theory. TheT
c variation on approaching the MIT and the relation between Mooij's rule and the superconducting properties are discussed. 相似文献
11.
Thin films of aluminium oxide were deposited on ferrite (Ni
x
Zn1−x
Fe2O4) substrates by r.f. sputtering. The sputtered alumina films were not easily etched by hot phosphoric acid unlike readily
etchable films prepared by physical deposition techniques. Microanalytical characterization of unetched films, partially etched
films and interfacial regions was conducted to identify the microscopic features responsible for reluctant film etchability.
The post-etched films were categorized as easily, partially and un-etchable (EE, PE and U respectively) and were examined
using optical microscopy, SEM, XRD, EDS, XPS, AES, and TEM/STEM. TEM examination of cross-sections of partially etchable films
revealed a non-uniform crystalline phase at the film-substrate interface. Electron diffraction data identified the phase asη-alumina although AES and EDS results suggest that the interfacial phase also contained some iron. The occurrence and orientation
of theη-alumina phase was shown to depend on the orientation of the grains of the ferrite substrate. 相似文献
12.
R Viswanathan S N Yedave S T Bendre S M Kanetkar S M Chaudhari S B Ogale 《Bulletin of Materials Science》1991,14(2):435-441
Ion beam and thermally-induced interface reactions between highT
c superconducting thin film of Y1Ba2Cu3O7−x
and metal overlayer of Ag are studied with a view to control the interfacial property of contact resistance. The interface
reaction is induced by 100 keV Ar+ ion beam with different ion dose values ranging from 5 × 1013 to 3×1014 ions/cm2. The YBaCuO film-metal interface is characterized by using the small angle XRD to study the structural properties of the
interfacial phases. The electrical property of the interface, specifically contact resistance, has been investigated for different
dose values and thermal treatments. Three-probe vs four-probe configuration has been adopted to measure the contact resistance. 相似文献
13.
K. M. Reddy J. Hays S. Kundu L. K. Dua P. K. Biswas C. Wang V. Shutthanandan M. H. Engelhard X. Mathew A. Punnoose 《Journal of Materials Science: Materials in Electronics》2007,18(12):1197-1201
We report on the preparation and characterization of high purity manganese (3–9 wt.%) doped indium tin oxide (ITO, In:Sn = 90:10)
films deposited by sol–gel mediated dip coating. X-ray diffraction and selected area electron diffraction showed high phase
purity cubic In2O3 and indicated a contraction of the lattice with Mn doping. High-resolution transmission electron microscopy depicted a uniform
distribution of ∼20 nm sized independent particles and particle induced x-ray emission studies confirmed the actual Mn ion
concentration. UV-Vis diffuse reflectance measurements showed band gap energy of 3.75 eV and a high degree of optical transparency
(90%) in the 100–500 nm thick ITO films. X-ray photoelectron spectroscopy core level binding energies for In 3d5/2 (443.6 eV), Sn 3d5/2 (485.6 eV) and Mn 2p3/2 (640.2 eV) indicated the In3+, Sn4+ and Mn2+ oxidation states. Magnetic hysteresis loops recorded at 300 K yield a coercivity Hc ∼ 80 Oe and saturation magnetization Ms ∼ 0.39 μB/Mn2+ ion. High-temperature magnetometry showed a Curie temperature T
c > 600 K for the 3.2% Mn doped ITO film. 相似文献
14.
SiOx films produced from octamethylycyclodisiloxane (Si4O4C8H24, OMCTS) with oxygen carrier gas have a low contact angle. The surface energy of the SiOx films can be changed by controlling the plasma process. SiOxCyHz films were deposited on polycarbonate substrates by plasma enhanced chemical vapor deposition using OMCTS without oxygen carrier gas. The input power in the radio frequency plasma was changed to optimize the surface energy of the resulting SiOxCyHz film. The plasma diagnostics, surface energy and surface morphology were characterized by optical emission spectrometry, contact angle measurements and atomic force microscopy, respectively. The chemical properties of the coatings were examined by Fourier transform infrared spectroscopy. The surface energy of the SiOxCyHz films produced using a room temperature plasma process could be controlled by employing the appropriate intensity of excited neutrals, ionized atoms, molecules and energy (input rf power and bias), as well as the suitable dissociation of OMCTS. 相似文献
15.
Review, analysis, and generalization of experimental data on the electrical resistivity of solid solutions of α-titanium-oxygen
with an atomic content less than c
O ∼ 10 % is performed. Numerical values of dρ(c
O)/dc
O derivatives at temperatures of 77 and 300 K are obtained. The dependence dρ/dT as a function of ρ293 and of the total oxygen content is built at room temperatures; and the dρ/dT = f(ρ293) analytical function is proposed for titanium. For titanium, the Matthiessen rule is shown not to be fulfilled even for a
small amount of impurities. The experimental data on electrical resistivity of solutions of α-titanium-oxygen, titanium, and
monocrystalline titanium are approximated by an equation obtained within the framework of the two-band model approximation. 相似文献
16.
Properties of indium tin oxide films deposited on unheated polymer substrates by ion beam assisted deposition 总被引:1,自引:0,他引:1
The optical, electrical and mechanical properties of indium tin oxide (ITO) films prepared on polyethylene terephthalate (PET) substrates by ion beam assisted deposition at room temperature were investigated. The properties of ITO films can be improved by introducing a buffer layer of silicon dioxide (SiO2) between the ITO film and the PET substrate. ITO films deposited on SiO2-coated PET have better crystallinity, lower electrical resistivity, and improved resistance stability under bending than those deposited on bare PET. The average transmittance and the resistivity of ITO films deposited on SiO2-coated PET are 85% and 0.90 × 10− 3 Ω cm, respectively, and when the films are bent, the resistance remains almost constant until a bending radius of 1 cm and it increases slowly under a given bending radius with an increase of the bending cycles. The improved resistance stability of ITO films deposited on SiO2-coated PET is mainly attributed to the perfect adhesion of ITO films induced by the SiO2 buffer layer. 相似文献
17.
Andrew J. Clayton Cecile M. E. Charbonneau Wing C. Tsoi Peter J. Siderfin Stuart J. C. Irvine 《Science and Technology of Advanced Materials》2018,19(1):153-159
Thin film tin sulphide (SnS) films were produced with grain sizes greater than 1 μm using a one-step metal organic chemical vapour deposition process. Tin–doped indium oxide (ITO) was used as the substrate, having a similar work function to molybdenum typically used as the back contact, but with potential use of its transparency for bifacial illumination. Tetraethyltin and ditertiarybutylsulphide were used as precursors with process temperatures 430–470 °C to promote film growth with large grains. The film stoichiometry was controlled by varying the precursor partial pressure ratios and characterised with energy dispersive X-ray spectroscopy to optimise the SnS composition. X-ray diffraction and Raman spectroscopy were used to determine the phases that were present in the film and revealed that small amounts of ottemannite Sn2S3 was present when SnS was deposited on to the ITO using optimised growth parameters. Interaction at the SnS/ITO interface to form Sn2S3 was deduced to have resulted for all growth conditions. 相似文献
18.
We have studied the structure, electric resistance, and magnetoresistance of 30-nm-thick (110)La0.67Ca0.33MnO3 (LCMO) films grown by laser deposition on (001)-oriented LaAlO3 substrates. The unit cell parameters a and b (along the [100] and [010]LCMO axes, respectively) of these manganite films are significantly (by ∼1.2%) increased as compared
to the corresponding values in the pseudocubic unit cell of bulk stoichiometric LCMO crystals. At T < 150 K, the temperature dependence of the resistivity of LCMO films is well described by the relation ρ = ρ1 + ρ2 (H) T
4.5. The value of ρ 2 decreases with increasing magnetic field and is close to the analogous coefficient for manganite films
grown on substrates with small lattice misfit. 相似文献
19.
The conditions necessary for the formation of Nb
3
Ge by low-pressure rf sputtering with a superconducting transition temperatureT
c
>21 K have been investigated. Samples have been deposited onto cooled substrates so that the film is first amorphous and then is crystallized by a subsequent annealing, and onto hot substrates, in which case the film is crystalline upon deposition. The highestT
c
samples were obtained for a substrate temperature of 735±25° C. The optimum substrate temperature is the same as the optimum annealing temperature for crystallizing films which were first deposited onto cooled substrates. Special conditions are necessary for the formation of single-phase A15 samples of Nb
3
Ge with an optimumT
c
. We have utilized the collisions that the sputtered atoms undergo with the sputtering gas molecules to thermalize the sputtered atoms. We report here on sputtering in both krypton and in argon. 相似文献
20.
The structure of polyethyleneterephthalate bristles drawn about five times in the amorphous state and subsequently crystallized
at temperatures between 100 and 260‡ C has been studied by means of small-angle X-ray scattering. In addition density, heat
of fusion and wide-angle scattering behaviour were measured. For comparison, similar experiments were carried out with undrawn
samples. The results showed that the degree of crystallinity of PET cannot be calculated from density data on the basis of
a simple two-phase model, since the effective densitiesρ
c
*
andρ
a
*
of the crystalline and amorphous regions depend strongly on crystallization and drawing conditions. With rising crystallization
temperature the size of the mosaic blocks building up the crystalline layers and their longitudinal mutual order increase
whereas the volume fraction of the crystalline region is only rather slightly effected by the annealing temperature. The difference
between the effective densityρ
c
*
and the “X-ray density”ρ
c of the crystalline layers is supposed to be caused by lattice vacancies in the boundaries of the mosaic blocks. 相似文献