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1.
Yuanjie Li Xiaofen Hu Zilong Liu Jiangbo Ren 《Journal of Materials Science: Materials in Electronics》2012,23(2):408-412
Amorphous In–Ga–ZnO thin films were deposited on quartz glass substrate at room temperature utilizing radio frequency magnetron sputtering
technique. Sputtering power and oxygen flow rate effects on the physical properties of the In–Ga–ZnO films were systematically investigated. It is shown the film deposition rate and the conductivity of the In–Ga–ZnO films increased with the sputtering power. The as-grown In–Ga–ZnO films deposited at 500 W exhibited the Hall mobility of 17.7 cm2/Vs. Average optical transmittance of the In–Ga–ZnO films is greater than 80% in the visible wavelength. The extracted optical band gap of the In–Ga–ZnO films increased from 3.06 to 3.46 eV with increasing the sputtering power. The electrical properties of the In–Ga–ZnO films are greatly dependent on the O2/Ar gas flow ratio and post-growth annealing process. Increasing oxygen flow rate converted the In–Ga–ZnO films from semiconducting to semi-insulating, but the resistivity of the films was significantly reduced after being annealed
in vacuum. Both the as-grown and annealed In–Ga–ZnO films show n-type electrical conductivity. 相似文献
2.
B. L. Zhu D. W. Zeng J. Wu W. L. Song C. S. Xie 《Journal of Materials Science: Materials in Electronics》2003,14(8):521-526
Undoped and In-doped ZnO nanoparticles were produced by renovated hybrid induction and laser heating (HILH) in this study from Zn–In alloy, with different mole ratios, as the raw material in a flowing mixed gas atmosphere of Ar+O2. The morphological characteristics, phase microstructure, and chemical state of In-doped ZnO nanoparticles were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The change in electrical resistance of thick film based on the In-doped ZnO nanoparticles and their gas sensitivities to volatile organic compounds (VOCs), benzene, acetone, ethyl alcohol, toluene, and xylene, as a function of temperature were measured in the temperature range of 200–500 °C, and compared with the undoped thick film. The results showed that the In-doped ZnO has lower resistance and higher sensitivity than that of the undoped ZnO. This was probably due to the fact that the In3+ ions, replacing the Zn2+ ions in the ZnO lattice, resulted in an increase of the concentration of free electrons followed by an increase of the adsorbed oxygen. Among the types of In-doped ZnO, 4.58 at % In-doped ZnO had the lowest resistance, and had the highest sensitivity. On increasing the concentration of In into ZnO, its resistance increased, while the sensitivity decreased. The sensitivity of the 4.58 at % In-doped ZnO to VOCs was in the order of acetone>alcohol>xylene>toluene> benzene at an operating temperature of 420 °C. 相似文献
3.
Thin metallic films of Zn and In/Zn were deposited onto glass substrates by thermal evaporation under vacuum. The metallic films were submitted to a thermal oxidation in air, at 623 K, for different oxidation times (30–90 min), in order to be oxidized. Structural and morphological analyses (X-ray diffraction, transmission electron microscopy and scanning electron microscopy) revealed that the obtained undoped and In-doped ZnO thin films possess a polycrystalline structure. Transmission spectra were recorded in spectral domain from 280 to 1400 nm. The influence of In doping and oxidation parameters as well, on the optical parameters (transmittance, optical bandgap, Urbach energy) were analysed. It was clearly evidenced that by In doping, the optical properties of ZnO films were improved. The temperature dependence of electrical conductivity was studied using surface-type cells with Ag electrodes. The obtained results indicate that In-doped ZnO films exhibit an enhancement of electrical conductivity with few orders of magnitude when compared with non-doped ones. 相似文献
4.
V. B. Patil S. G. Pawar S. L. Patil S. B. Krupanidhi 《Journal of Materials Science: Materials in Electronics》2010,21(4):355-359
The compositional, structural, microstructural, dc electrical conductivity and optical properties of undoped zinc oxide films
prepared by the sol–gel process using a spin-coating technique were investigated. The ZnO films were obtained by 5 cycle spin-coated
and dried zinc oxide films followed by annealing in air at 600 °C. The films deposited on the platinum coated silicon substrate
were crystallized in a hexagonal wurtzite form. The energy-dispersive X-ray (EDX) spectrometry shows Zn and O elements in
the products with an approximate molar ratio. TEM image of ZnO thin film shows that a grain of about 60–80 nm in size is really
an aggregate of many small crystallites of around 10–20 nm. Electron diffraction pattern shows that the ZnO films exhibited
hexagonal structure. The SEM micrograph showed that the films consist in nanocrystalline grains randomly distributed with
voids in different regions. The dc conductivity found in the range of 10−5–10−6 (Ω cm)−1. The optical study showed that the spectra for all samples give the transparency in the visible range. 相似文献
5.
In this study, pure ZnO microbullets, ZnO–ZnFe2O4 composite, and ZnO–Fe2O3–ZnFe2O4 composite with micron structured balloons, rods, and particles were prepared by a simple solvent thermal process using methanol
or ethanol as solvents. The influence of solvents on the composition and morphology of the products was studied, and their
gas-sensing properties were also investigated. The morphology of ZnO microbullets synthesized in ethanol is similar to but
more uniform than that of ZnO microbullets synthesized in methanol. The Fe-doped ZnO synthesized in ethanol contains many
micron particles homogeneously dispersing on the surface of the microbullets, which is composed of hexagonal wurtzite ZnO
and franklinite ZnFe2O4, while Fe-doped ZnO prepared in methanol consists of micron structured balloons, rods, and particles, which is composed of
hexagonal wurtzite ZnO, hematite Fe2O3, and franklinite ZnFe2O4. Compared with pure ZnO and ZnO–ZnFe2O4 composite, the ZnO–Fe2O3–ZnFe2O4 composite presented high response, rapid response/recovery characteristics, good selectivity, and excellent stability to
acetone at relatively low operating temperature of 190 °C. This sensor could detect acetone in wide range of 1–1000 ppm, which
was expected to be a promising gas sensor for detecting acetone. 相似文献
6.
Frederick Ojo Adurodija Lynne Semple Ralf Brüning 《Journal of Materials Science》2006,41(21):7096-7102
Amorphous indium oxide (In2O3) and 10-wt% SnO2 doped In2O3 (ITO) thin films were prepared by pulsed-laser deposition. These films were crystallized upon heating in vacuum at an effective heating rate of 0.00847 °C/s, while the evolution of the structure was observed by in situ X-ray diffraction measurements. Fast crystallization of the films is observed in the temperature ranges 165–210 °C and 185–230 °C for the In2O3 and ITO films, respectively. The crystallization kinetics is described by a reaction equation, with activation energies of 2.31 ± 0.06 eV and 2.41 eV and order of reactions of 0.75 ± 0.07 and 0.75 for the In2O3 and ITO films, respectively. The structures of the films observed here during heating are compared with those obtained upon film growth at different temperatures. The resistivity of the films depends on the evolution of the structure, the oxygen content and the activation of tin dopants in the films. A low resistivity of 5.5 × 10−4 Ω cm was obtained for the In2O3 and ITO films at room temperature, after annealing to 250 °C the resistivity of the ITO film reduces to 1.2 × 10−4 Ω cm. 相似文献
7.
Effect of substrate temperature on the photoelectrochemical responses of Ga and N co-doped ZnO films
Sudhakar Shet Kwang-Soon Ahn Heli Wang Ravindra Nuggehalli Yanfa Yan John Turner Mowafak Al-Jassim 《Journal of Materials Science》2010,45(19):5218-5222
Ga–N co-doped ZnO thin films with reduced bandgaps were deposited on F-doped tin-oxide-coated glass by radio-frequency magnetron
sputtering at different substrate temperatures in mixed N2 and O2 gas ambient. We found that Ga–N co-doped ZnO films exhibited enhanced crystallinity when compared to undoped ZnO films grown
under the same conditions. Furthermore, Ga–N co-doping ensured enhanced N-incorporation ZnO thin films as the substrate temperature
is increased. As a result, Ga–N co-doped ZnO thin films exhibited much improved photoelectrochemical (PEC) response, compared
to ZnO thin films. Our results therefore suggest that the passive co-doping approach could be a means to improve PEC response
for bandgap-reduced wide-bandgap oxides through impurity incorporation. 相似文献
8.
The synthesis of the undoped ZnO and ZnO–Sn2O3 composites prepared by conventional solid-state reaction method has been reported. Besides, the effect of increasing Sn2O3 content from 5 to 15 wt% on structural, optical, dielectric and electrical properties of the ZnO–Sn2O3 composites has also been investigated. In fact, the X-ray diffraction analysis indicates that the as-prepared ZnO–Sn2O3 composites may contain some combined phases such as SnO and Zn2SnO4. The atomic force microscopy shows that the surfaces of the composites are rough. The band gap energy seems to depend on the amount of Sn2O3 addition, with the maximum obtained at 15 wt% Sn2O3. Concerning the optical band gap, it has been found to be in the range of 3.18–3.93 eV. The dielectric loss was found to decrease with the increase in frequency. The results obtained from the ac-conductivity revealed that the values of σ(ω) increases with the Sn2O3 adding content. The dc-conductivity of all the composites increases with the increase in temperature. The electrical conductivity was analyzed with the power law, and agrees with the correlation barrier hopping model. 相似文献
9.
A discussion of the optical properties of two systems of dielectric films i.e. In2O3 and of mixed oxides In2O3−MoO3 system is presented. Film thickness, substrate temperature, annealing and composition (in molar%) have a profound effect
on the structure and optical properties of these films. The decrease in optical band gap with the increase in film thickness
of In2O3 is interpreted in terms of incorporation of oxygen vacancies in the In2O3 lattice. The decrease in optical band gap with the increase in substrate temperature and annealing of In2O3 thin films is ascribed to the release of trapped electrons by thermal energy or by the outward diffusion of the oxygen-ion
vacancies, which are quite mobile even at low temperature. For the mixed oxides In2O3−MoO3 system the results are found to be compatible with the reduction in the value of optical band gap of these materials as the
molar fraction of MoO3 increases in the In2O3 thin films and is attributed to the incorporation of Mo(VI) ions in an In2O3lattice that causes the indium orbital to become a little less tightly bound. The decrease in optical band gap of mixed oxides
In2O3−MoO3 system, with increasing film thickness is interpreted in terms of incorporation of oxygen vacancies in both In2O3 and MoO3 lattice which are also believed to be the source of conduction electrons in In2O3–MoO3 complex. The decrease in optical band gap with increasing substrate temperature and annealing of mixed oxides In2O3−MoO3 system is due to the increasing concentration of oxygen vacancies, formation of indium and molybdenum species of lower oxidation
state and indium interstitials. The blue colouration of mixed oxides In2O3–MoO3 samples is due to the inter-electron transfer from oxygen 2p to molybdenum 4d level due to which Mo species of lower oxidation
states are formed. 相似文献
10.
Fabrication and comparative study of top-gate and bottom-gate ZnO–TFTs with various insulator layers
XinAn Zhang JingWen Zhang WeiFeng Zhang Xun Hou 《Journal of Materials Science: Materials in Electronics》2010,21(7):671-675
Transparent ZnO thin film transistors (ZnO–TFTs) with different structures and dielectric layers were fabricated by rf magnetron
sputtering. The PbTiO3, AlO
x
, SiN
x
and SiO
x
films were attempted to serve as the gate dielectric layers in the devices, respectively, and XRD was employed to investigate
the crystal structure of ZnO films deposited on these dielectric layers. The optical properties of transparent TFTs were measured
and revealed the average transmittance ranged from 60 to 80% in the visible part of the spectrum. Electrical measurement shows
the properties of the ZnO–TFTs have great relations with the device structure. The bottom-gate TFTs have better behaviors
than top-gate ones with the mobility, threshold voltage and the current on/off ratio of 18.4 cm2 V−1 s−1, −0.7 V and 104, respectively. The electrical difference of the devices may be due to different character of the interface between the channel
and dielectric layers. 相似文献
11.
设计了一系列名义组成为Zn4Sb3-xInx(0~0.08,Δx=0.02)的In掺杂β-Zn4Sb3基块体材料,并用真空熔融-随炉冷却-放电等离子体烧结工艺成功制备出无裂纹的In掺杂单相β-Zn4Sb3基块体材料.300~700K内材料的电热输运特性表明,In杂质对Zn4Sb3化合物的Sb位掺杂可导致载流子浓度和电导率大幅度增大、高温下本征激发几乎消失和晶格热导率显著降低,x=0.04和0.08的Zn4Sb3-xInx的In掺杂β-Zn4Sb3化合物700K时晶格热导率均仅为0.21W/(m·K).与纯β-Zn4Sb3块体材料相比,所有In掺杂β-Zn4Sb3基块体材料的ZT值均显著增大,x=0.06的Zn4Sb3-xInx的In掺杂β-Zn4Sb3基块体材料700K时ZT值达到1.13,提高了69%. 相似文献
12.
Polycrystalline ZnO-In2O3 thin films were prepared by thermal oxidation in air of metallic Zn-In films deposited onto glass substrates by thermal evaporation under vacuum. Different oxidation conditions (oxidation temperature, oxidation time, heating rate) were used in order to prepare homogeneous films that can be used as gas sensors. Polycrystalline structure of the as-obtained films was confirmed by X-ray and electron diffraction investigations. The electrical conductivity of various thin film samples ranged between 0.84 and 6.44 (Ω cm)− 1.Gas sensitivity to six different gasses (ammonia, methane, LPG, acetone, ethanol and formaldehyde) was evaluated and it was found that the highest sensitivity was obtained for ammonia. 相似文献
13.
Zhonghua Deng Changgang Huang Jiquan Huang Meili Wang Hong He Hai Wang Yongge Cao 《Journal of Materials Science: Materials in Electronics》2010,21(10):1030-1035
Aluminum doped zinc oxide (AZO) films were deposited on quartz substrates by radio-frequency magnetron co-sputtering method
with ZnO and Al2O3 ceramic targets. The structural, optical and electrical properties of these films as a function of the Al content were investigated.
XRD results reveal that the AZO films are wurtzite structure with (002) preferred orientation. The average transmittance of
all the films is higher than 80% in a wide wavelength range from 400 to 1,500 nm. The band gap energy, calculated from their
optical absorption spectra, is in the range of 3.50–3.66 eV depending on the Al content. Doping of Al3+ in the ZnO makes the film surface roughness decrease. The dopant Al3+ acts as electron donor by which the electrical conductivity and carrier concentration of the films are obviously increased
until the Al3+ reaches its saturation content of about 4.50 at.%. 相似文献
14.
Reza Keshavarzi Majid Moghadam Shahram Tangestaninejad Hamid Reza Fallah Hamed Reza Modayemzadeh 《Materials Research Bulletin》2011,46(4):615-620
In this work, the preparation of In2O3-ZnO thin films by electron beam evaporation technique on glass substrates is reported. Optical and electrical properties of these films were investigated. The effect of dopant amount and annealing temperature on the optical and electrical properties of In2O3-ZnO thin films was also studied. Different amount of ZnO was used as dopant and the films were annealed at different temperature. The results showed that the most crystalline, transparent and uniform films with lowest resistivity were obtained using 25 wt% of ZnO annealed at 500 °C. 相似文献
15.
Improvement of electrical properties of V2O5 modified ZnO ceramics by Mn-doping for varistor applications 总被引:1,自引:0,他引:1
Choon-Woo Nahm 《Journal of Materials Science: Materials in Electronics》2008,19(10):1023-1029
The dependence of microstructure, electrical properties, dielectric characteristics, and stability of conduction characteristics
in ternary ZnO–V2O5–Mn3O4 system on the amount of Mn3O4 present in them was investigated. For all compositions studied, the microstructure of the ternary ZnO–V2O5–Mn3O4 system consisted of mainly ZnO grains and Zn3(VO4)2 as a secondary phase. The incorporation of Mn3O4 to the binary ZnO–V2O5 system was found to restrict abnormal grain growth of ZnO. The breakdown field in the electric field–current density characteristics
increased from 175 to 4,635 V/cm with the increase of Mn3O4 amount. The ternary system doped with 0.5 mol% Mn3O4 exhibited the highest non-ohmic properties, in which the non-ohmic coefficient is 22.4 and the leakage current density is
0.22 mA/cm2. Furthermore, the sample doped with 0.5 mol% Mn3O4 was found to possess 0.43 × 1018/cm3 in donor density and 2.66 eV in barrier height. 相似文献
16.
Y2O3-doped ZrO2 (YZ) thin films were prepared on alumina substrates by the dip-coating process. The dip-coating solution consisted of a homogeneous
sol, and was prepared by using the respective chlorides as raw materials, with ethylene glycol, 2-butanol and distilled water
as solvents. The thin films containing 0–20 mol % Y2O3 were successfully produced by thermal treatment above 600 °C. The characterization for the film preparation was performed
by means of thermogravimetric–differential thermal analysis for the thermal analysis, and scanning electron microscopy for
the morphological analysis and thickness measurements. The properties of the films were characterized in terms of a study
of the crystalline phase, the crystallite size, the microstructure and the electrical conductivity by using X-ray diffraction,
scanning electron microscopy and the complex impedance techniques. In all YZ thin films, the tetragonal phase was stable at
low temperatures as a result of the crystallite size effect. However, at higher temperatures, the tetragonal phase was transformed
into either the monoclinic phase or the cubic phase, depending on the doping concentration. The YZ thin film of 8 mol% Y2O3 content was stabilized to almost cubic phase at 1000 °C. Resonable conductivity behaviour at YZ was observed for the YZ thin
films. The electrical conductivity of YZ thin films was similar to the values of the sintered body.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
17.
With the aim of producing fine-grained manganese–zinc (Mn–Zn) ferrite at the end of a calcination process at moderate temperatures,
this study consisted, at first, of an “electrochemically designed” powder mixing by wet-ball milling a mixture of manganese
(MnO2), zinc (ZnO), and iron (Fe2O3 granules produced by an acid recovery unit of a Brazilian steelmaker, milled to fine sizes using alkaline media) –based raw
materials. This mixing/milling resulted in improved size reduction when compared to milling without any alkali addition. Further,
noticeable size reduction was achieved when elemental Zn was used in place of ZnO, especially when ammonia was used as the
medium. Calcination of the alkaline-milled mixture of MnO2 + ZnO + Fe2O3 at 1200 °C allowed obtaining well-crystallized single-phase Mn–Zn ferrite, whereas calcination of the MnO2 + ZnO + Fe2O3 mill-mixed in 100% NH4OH at 1200 °C produced the highest saturation magnetization in the as-calcined state. 相似文献
18.
Xiaodan Zhang Qian HuangYanfeng Wang Yang LiuXinliang Chen Ying Zhao 《Thin solid films》2011,520(4):1186-1191
We present double layer structures consisting of ZnO:B/ZnO:B (BZO) and In2O3:Mo (IMO)/BZO films. The structure offers the unique opportunity of separating the conductivity of transparent conductive oxides from their light scattering behavior and allows their optimization for use in thin film solar cells. The layers serve as carrier transport and light trapping layers, respectively. BZO films were prepared by mid-frequency magnetic sputtering from a ZnO:B2O3 ceramic target. In order to enhance the conductivity of the BZO films, hydrogen was introduced into the sputtering atmosphere. Introducing hydrogen increased the mobility of the BZO-based double layer films to near 30 cm2/V•s. Efficient scattering was achieved by etching the film in dilute hydrochloric acid. IMO films were also tested as the transport layer. An unconventional surface morphology was obtained by etching the IMO/BZO double layer film. Using this cascading multilayer structure IMO/BZO film as the front contact in a-Si:H solar cell, 20.4% and 7.4% enhancements in short circuit current density were obtained compared to smooth IMO films and textured single layer BZO films. 相似文献
19.
A study of crystallographic phases in non-stoichiometric (oxygen deficiency) indium oxide thin films
Indium oxide is a well-known transparent conductive oxide (TCO) in its stoichiometric composition (In2O3). Its electrical and optical properties are strongly influenced by the chemical composition. This work focuses on an experimental investigation of the crystallographic phases in non-stoichiometric (oxygen deficiency) compositions of indium oxide thin films. The thin films were deposited at 300 °C by reactive sputtering of pure indium target at different oxygen gas flow rates on Si substrates. Two different phases are identified only in the non-stoichiometric compositions: metallic indium- and crystalline indium-rich oxide. The metallic indium phase appears as nano-crystals, a few nano-meters in diameter, evenly dispersed and occupies only 1 vol. % of the film. These metallic nano-particles have a negligible effect on the optical transparency and electrical conductivity of the films. The indium-rich oxide (InxOy) phase which occupies about 99 vol. % of the film has the bixbyite crystallographic structure and average grain size of about 50 nm. This phase has a pronounced effect on improving the TCO figure-of-merit (FM) relative to stoichiometric crystalline In2O3 films due to a higher increase of the electrical conductivity than the decrease of the optical transparency. 相似文献
20.
P. P. Hankare M. R. Asabe P. A. Chate K. C. Rathod 《Journal of Materials Science: Materials in Electronics》2008,19(12):1252-1257
Solar cell technologically important binary indium selenide thin film has been developed by relatively simple chemical method.
The reaction between indium chloride, tartaric acid, hydrazine hydrate and sodium selenosulphate in an aqueous alkaline medium
at room temperature gives deposits In2Se3 thin film. Various preparative parameters are discussed. The as grown films were found to be transparent, uniform, well adherent,
red in color. The prepared films were studied using X-ray diffraction, scanning electron microscopy, atomic absorption spectroscopy,
Energy dispersive atomic X-ray diffraction, optical absorption and electrical conductivity properties. The direct optical
band gap value Eg for the films was found to be as the order of 2.35 eV at room temperature and having specific electrical conductivity of
the order of 10−2 (Ω cm)−1 showing n-type conduction mechanism. The utility of the adapted technique is discussed from the point of view of applications
considering the optoelectric and structural data obtained. 相似文献