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1.
Improvement of the light output and contact resistance of InGaN-based light-emitting diodes based on tantalum-doped indium tin oxide as p-type electrodes
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This paper reports that highly transparent and low
resistance tantalum-doped indium tin oxide (Ta-doped ITO) films
contacted to p-type GaN have been prepared by the electron-beam
evaporation technique. The Ta-doped ITO contacts become Ohmic with
a specific contact resistance of $\sim 5.65\times 10^{ - 5}$~$\Omega
\cdot$cm$^{2}$ and show the transmittance of $\sim $98% at a
wavelength of 440~nm when annealed at 500~\du. Blue light emitting
diodes (LEDs) fabricated with Ta-doped ITO p-type Ohmic contact layers
give a forward-bias voltage of 3.21~V at an injection current of
20~mA. It further shows that the output power of LEDs with
Ta-doped ITO contacts is enhanced 62% at 20~mA in comparison with
that of LEDs with conventional Ni/Au contacts. 相似文献
2.
By using a sol-gel clue, a set of polycrystalline perovskite samples
La$_{1 - x}$Ag$_{x}$MnO$_{3}$ with a nominal doping level $x$ ranging
from 0.05 to 0.45 has been synthesized. The chemical composition and
the magnetism of the samples were investigated. A little Ag was found
seeping from the samples in the sintering process when the doping
level exceeded 0.05 and the sintering temperature was higher than
700\du\, resulting in the samples being in multiphase. The magnetic
transition points of the samples have been found to decrease with
increasing sintering temperature. A concentration-dependent $T_{\rm
c}$ similar to that of bivalent metal ion doped perovskite, has been
obtained. We believe that the Ag seeping in the sintering process is
responsible for those magnetic characteristics. 相似文献
3.
A. S. Bugaev V. A. Astapenko E. S. Manuilovich S. V. Sakhno E. S. Khramov A. V. Yakovets 《Doklady Physics》2018,63(2):55-57
The process of scattering of radiation by indium?tin oxide (ITO) nanoparticles is theoretically studied at various degrees of doping and for different radii of nanoparticles. Qualitative conclusions are made about the character of the dependence of the scattering cross section on the frequency with variation of the particle size and the percentage content of tin. The prospects of using ITO nanoparticles as an active substance in optical sensors are estimated. 相似文献
4.
Synthesis and high temperature thermoelectric transport properties of Si-based type-I clathrates
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N-type Si-based type-I clathrates with different Ga content were
synthesized by combining the solid-state reaction method, melting method
and spark plasma sintering (SPS) method. The effects of Ga
composition on high temperature thermoelectric transport properties
were investigated. The results show that at room
temperature, the carrier concentration decreases, while the carrier
mobility increases slightly with increasing Ga content. The
Seebeck coefficient increases with increasing Ga content.
Among all the samples, Ba7.93Ga17.13Si28.72 exhibits
higher Seebeck coefficient than the others and reaches -135~μ
V.K-1 at 1000 K. The sample prepared by this method
exhibits very high electrical conductivity, and reaches 1.95×
105S.m-1 for
Ba8.01Ga16.61Si28.93 at room temperature. The thermal
conductivity of all samples is almost temperature independent in the
temperature range of 300--1000~K, indicating the behaviour of a typical
metal. The maximum {ZT} value of 0.75 is obtained at 1000~K for the compound
Ba7.93Ga17.13Si28.72. 相似文献
5.
A low temperature synthesis technique to prepare indium tin oxide (ITO) nanoparticles by the polyol process is proposed. On examining the phase formation of ITO nanoparticles in polyols and alcohols such as ethylene glycol, trimethylene glycol, and 1-heptanol, it was found that ITO nanoparticles could be synthesized directly without any post--annealing treatments at 175 °C in 1-heptanol. The morphology of the particles is influenced by the type of polyol. The composition of Sn in the ITO system could be easily controlled by simply varying the In/Sn precursor ratio in 1-heptanol. The low temperature synthesis method has enabled the formation of highly crystalline ITO nanoparticles with diameters less than 25 nm even at annealing temperatures as high as 700 °C. 相似文献
6.
The relationship between charge-density-wave (CDW) and superconductivity (SC), two vital physical phases in condensed matter physics, has always been the focus of scientists' research over the past decades. Motivated by this research hotspot, we systematically studied the physical properties of the layered telluride chalcogenide superconductors CuIr$_{2-x}$Al$_{x}$Te$_{4}$ ($0 \leqslant x \leqslant 0.2$). Through the resistance and magnetization measurements, we found that the CDW order was destroyed by a small amount of Al doping. Meanwhile, the superconducting transition temperature ($T_{\rm c}$) kept changing with the change of doping amount and rose towards the maximum value of 2.75 K when $x=0.075$. The value of normalized specific heat jump ($\Delta C/\gamma T_{\rm c}$) for the highest $T_{\rm c}$ sample CuIr$_{1.925}$Al$_{0.075}$Te$_{4}$ was 1.53, which was larger than the BCS value of 1.43 and showed the bulk superconducting nature. In order to clearly show the relationship between SC and CDW states, we propose a phase diagram of $T_{\rm c}$ vs. doping content. 相似文献
7.
Enhancement of magnetic and dielectric properties of low temperature sintered NiCuZn ferrite by Bi2O3-CuO additives
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With a series of 1.0 wt%Bi$_{2}$O$_{3}$-$x$ wt% CuO ($x =0.0$, 0.2, 0.4, 0.6, and 0.8) serving as sintering additives, Ni$_{0.23}$Cu$_{0.32}$Zn$_{0.45}$Fe$_{2}$O$_{4}$ ferrites are successfully synthesized at a low temperature (900 $^\circ$C) by using the solid state reaction method. The effects of the additives on the phase formation, magnetic and dielectric properties as well as the structural and gyromagnetic properties are investigated. The x-ray diffraction (XRD) results indicate that the added Bi$_{2}$O$_{3}$-CuO can lower the synthesis temperature significantly without the appearing of the second phase. The scanning electron microscope (SEM) images confirm that Bi$_{2}$O$_{3}$ is an important factor that determines the sintering behaviors, while CuO affects the grain size and densification. With CuO content $x=0.4$ or 0.6, the sample shows high saturation magnetization, low coercivity, high real part of magnetic permeability, dielectric permittivity, and small ferromagnetic resonance linewidth ($\Delta H$). The NiCuZn ferrites are a promising new generation of high-performance microwave devices, such as phase shifters and isolators. 相似文献
8.
F.O. Adurodija R. Brüning I.O. Asia H. Izumi T. Ishihara H. Yoshioka 《Applied Physics A: Materials Science & Processing》2005,81(5):953-957
The properties of indium tin oxide (ITO) thin films, deposited at room temperature by simultaneous pulsed laser deposition (PLD), and laser irradiation of the substrate are reported. The films were fabricated from different Sn-doped In2O3 pellets at an oxygen pressure of 10 mTorr. During growth, a laser beam with an energy density of 0, 40 or 70 mJ/cm2 was directed at the middle part of the substrate, covering an area of ∼1 cm2. The non-irradiated (0 mJ/cm2) films were amorphous; films irradiated with 40 mJ/cm2 exhibited microcrystalline phases; and polycrystalline ITO films with a strong 〈111〉> preferred orientation was obtained for a laser irradiation density of 70 mJ/cm2. The resistivity, carrier density, and Hall mobility of the ITO films were strongly dependent on the Sn doping concentration and the laser irradiation energy density. The smallest resistivity of ∼1×10-4 Ω cm was achieved for a 5 wt % Sn doped ITO films grown with a substrate irradiation energy density of 70 mJ/cm2. The carrier mobility diminished with increasing Sn doping concentration. Theoretical models show that the decrease in mobility with increasing Sn concentration is due to the scattering of electrons in the films by ionized centers. PACS 81.15.Fg; 73.61.-r; 73.50.-h 相似文献
9.
10.
Laser-induced breakdown spectroscopy (LIBS) is an effective method for nondestructive rapid element analysis in a wide range
of media in situ. We use the LIBS technique for quantitative analysis of indium tin oxide (ITO) films, which are transparent
conducting materials widely used in industry. The plasma is generated by focusing a Nd:YAG laser pulse with a duration of
10 ns and a wavelength of 1064 nm onto the ITO-sample surface. We perform test experiments to define optimum values of the
laser-pulse energy and the time delay between the laser pulse and the beginning of the LIBS spectra acquisition. Next, by
the calibration-free Boltzmann plot method, we assess the plasma temperature and finally calculate the content of In and Sn
in the test ITO specimen, and this agrees well with real concentration values. 相似文献
11.
This paper reports the preparation of antimony doped tin oxide crystalline powders by chemical coprecipitation method. The influence of sintering temperature and the sintering retention time on the thermal infrared emissivity is analysed. The thermal infrared reflectivity is measured and the optimum doping concentration is proposed. 相似文献
12.
This paper reports that single-phase γ-Y2Si2O7 is prepared via a sufficient blending and cold-pressed sintering technique from Y2O3 powder and SiO2 nanopowder. It studies the dielectric properties of γ-Y2Si2O7 as a function of the temperature and frequency. The γ-Y2Si2O7 exhibits low dielectric loss and non-Debye relaxation behaviour from 25 to 1400℃ in the range of 7.3-18 GHz. The mechanism for polarization relaxation of the as-prepared γ-Y2Si2O7 differing from that of SiO 2 is explained. Such particular dielectric properties could potentially make specific attraction for extensive practical applications. 相似文献
13.
We have carried out a theoretical study of double-5-doped InAlAs/InGaAs/InP high electron mobility transistor (HEMT) by means of the finite differential method. The electronic states in the quantum well of the HEMT are calculated self-consistently. Instead of boundary conditions, initial conditions are used to solve the Poisson equation. The concentration of two-dimensional electron gas (2DEG) and its distribution in the HEMT have been obtained. By changing the doping density of upper and lower impurity layers we find that the 2DEG concentration confined in the channel is greatly affected by these two doping layers. But the electrons depleted by the Schottky contact are hardly affected by the lower impurity layer. It is only related to the doping density of upper impurity layer. This means that we can deal with the doping concentrations of the two impurity layers and optimize them separately. Considering the sheet concentration and the mobility of the electrons in the channel, the optimized doping densities are found to be 5 × 10^12 and 3× 10^12 cm^-2 for the upper and lower impurity layers, respectively, in the double-5-doped InAlAs/InGaAs/InP HEMTs. 相似文献
14.
Power dissipation characteristics of great power and super high speed semiconductor switch
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The power dissipation characteristics of pulsed power switch reversely switched dynistors (RSDs) are investigated in this paper. According to the expressions of voltage on RSD, derived from the plasma bipolar drift model and the RLC circuit equations of RSD main loop, the simulation waveforms of current and voltage on RSD are acquired through iterative calculation by using the fourth order Runge-Kutta method, then the curve of transient power on RSD versus time is obtained. The result shows that the total dissipation on RSD is trivial compared with the pulse discharge energy and the commutation dissipation can be nearly ignored compared with the quasi-static dissipation. These characteristics can make the repetitive frequency of RSD increase largely. The experimental results prove the validity of simulation calculations. The influence factors on power dissipation are discussed. The power dissipation increases with the increase of the peak current and the n-base width and with the decrease of n-base doping concentration. In order to keep a low power dissipation, it is suggested that the n-base width should be smaller than 320μm when doping concentration is 1.0×10^14cm^-3 while the doping concentration should be higher than 5.8×10^13cm^-3 when n-base width is 270μm. 相似文献
15.
We propose a substrate-free focal plane array (FPA) in
this paper. The solid substrate is completely removed, and the
microcantilevers extend from a supporting frame. Using finite
element analysis, the thermal and mechanical characterizations
of the substrate-free FPA are presented. Because of the large
decrease in thermal conductance, the supporting frame is temperature
dependent, which brings out a unique feature: the lower the thermal
conductance of the supporting frame is, the higher the energy
conversion efficiency in the substrate-free FPA will be. The results
from the finite element analyses are consistent with our
measurements: two types of substrate-free FPAs with pixel sizes
of 200× 200 and 60× 60~μ m2 are implemented
in the proposed infrared detector. The noise equivalent temperature
difference (NETD) values are experimentally measured to be 520 and
300~mK respectively. Further refinements are considered in various
aspects, and the substrate-free FPA with a pixel size of 30×
30~μ m2 has a potential of achieving an NETD value of
10~mK. 相似文献
16.
17.
Highly non-stoichiometric indium tin oxide (ITO) thin films were grown by pulsed energy beam deposition (pulsed laser deposition-PLD and pulsed electron beam deposition-PED) under low oxygen pressure. The analysis of the structure and electrical transport properties showed that ITO films with a large oxygen deficiency (more than 20%) are nanocomposite films with metallic (In, Sn) clusters embedded in a stoichiometric and crystalline oxide matrix. The presence of the metallic clusters induces specific transport properties, i.e. a metallic conductivity via percolation with a superconducting transition at low temperature (about 6 K) and the melting and freezing of the In-Sn clusters in the room temperature to 450 K range evidenced by large changes in resistivity and a hysteresis cycle. By controlling the oxygen deficiency and temperature during the growth, the transport and optical properties of the nanocomposite oxide films could be tuned from metallic-like to insulating and from transparent to absorbing films. 相似文献
18.
AlGaInP thin-film LED with omni-directionally reflector and ITO transparent conducting n-type contact 总被引:1,自引:0,他引:1
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In this paper a novel A1GalnP thin-film light-emitting diode (LED) with omni-directionally reflector (ODR) and transparent conducting indium tin oxide (ITO) n-type contact structure is proposed, and fabrication process is developed. This reflector is realized with the combination of a low-refractive-index dielectric layer and a high reflectivity metal layer. This allows the light emitted or internally reflected downwardly towards the GaAs substrate at any angle of incidence to be reflected towards the top surface of the chip. ITO n-type contact is used for anti-reflection and current spreading layers on the ODR-LED with ITO. The sheet resistance of the ITO films (95 nm) deposited on n- ohmic contact of ODR-LED is of the order 23.5Ω/△ with up to 90% transmittance (above 92% for 590-770 nm) in the visible region of the spectrum. The optical and electrical characteristics of the ODR-LED with ITO are presented and compared to conventional AS-LED and ODR-LED without ITO. It is shown that the light output from the ODR-LED with ITO at forward current 20mA exceeds that of AS-LED and ODR-LED without ITO by about a factor of 1.63 and 0.16, respectively. A favourable luminous intensity of 218.3 mcd from the ODR-LED with ITO (peak wavelength 620 nm) could be obtained under 20 mA injection, which is 2.63 times and 1.21 times higher than that of AS-LED and ODR-LED without ITO, respectively.[第一段] 相似文献
19.
根据红外辐射理论和薄膜光学原理计算了高品质ITO(indium tin oxide)导电膜的红外发射 率,其理论曲线与实测曲线基本符合. 并得出方块电阻小于30Ω时,ITO膜在红外波段8—14μ m的平均红外发射率理论值小于0.1.实际制备方块电阻小于10Ω的ITO膜具有优良的红外隐身 性能. 讨论了高品质ITO膜具有低红外发射率的物理机理,并提出了低红外发射率临界方块电 阻值,这有利於理论研究和工艺制备红外隐身ITO膜.
关键词:
红外发射率
ITO薄膜
理论计算
方块电阻 相似文献
20.
通过X-射线衍射及磁测量手段研究了Dy2AlFe13Mn3化合物的结构及磁性质。研究结果表明Dy2AlFe13Mn3化合物具有六角相的Th2Ni17型结构。通过X-射线热膨胀测定法发现Dy2AlFe13Mn3化合物在245到344K的温度范围内存在负热膨胀现象,其平均热膨胀系数为α=-1.1×10-4K-1K-1。在105到360K的温度范围内,通过比较磁性状态下的晶胞参数和由高温顺磁状态外延得到的低温顺磁状态下的晶胞参数间的差别计算了Dy2AlFe13Mn3化合物的本征磁致伸缩。结果表明Dy2AlFe13Mn3化合物的本征体磁致伸缩ωS在105到245K的温度范围内随着温度的升高而增大,由105K时的7.0×10-3 增加到245K时的9.1×10-3。随着温度的进一步升高,ωS反而减小。沿c轴方向的本征线磁致伸缩λc随着温度的升高而减小。基面内的本征线磁致伸缩λa在105到270K的温度范围内随着温度的升高而增大,从105K时的0.8×10-3增大到270K时的3.4×10-3,然后随着温度的进一步升高而减小。 相似文献