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Neutron detector based on an ITO/p-Si structure
Abstract
Neutron detectors based on ITO/p-Si structure are fabricated and investigated. The ITO layer is deposited on p-type (100)Si with resistivity 60Ωcm by DC reactive magnetron sputtering of a 90%In–10%Sn target at 450°C substrate temperature. The low temperature of the deposition process retains the large lifetime of the minority carriers in the Si wafer. The degenerately doped ITO layer functions as a metal. Due to contact potential difference between Si and ITO, an energy barrier for holes is formed at the interface. It is shown that using relatively low-resistivity silicon (50–100Ωcm), the requirements for neutron detection can be satisfied and that the ITO/p-Si structure with LiF (80%6Li enrichment) deposited directly on the ITO layer can be used for neutron detection. The relatively small depletion region width makes the detector insensitive to the background γ-field. This is an advantage compared to the conventional high-resistivity Si detectors.
... Under zero voltage, the top p-Si layer of sample A is depleted. The photo-generated carriers in this layer will be swept into ITO electrodes by the electric field, where the Scho-tky-barrier height of ITO contact to p-Si is 0.78 eV, measured by I-V model [12], which is in agreement with previous result [8]. But the photo-generated carriers in SiGe layer are diffusion limited and most of the carriers will be trapped at Si and SiGe interface due to the large lattice mismatch (4%) between Si and Ge [9]. ...
A simple and low-cost structure of voltage-tunable dual-band near-infrared photodetector (PD) has been proposed, in which the PDs were developed by using Si0.8Ge0.2/Si metal–semiconductor–metal (MSM) heterostructure. The Si0.8Ge0.2/Si layers were deposited by ultrahigh-vacuum chemical vapor deposition system and a transparent layer of indium–tin oxide (ITO) was used as a metal layer to enhance the entrance of photons. In this study, we found that only one band was detected with a peak wavelength located at 950nm at zero applied bias. When bias was increased to 1V, in contrast a dual-band was achieved, where two peak wavelengths were centered at 950- and 1150-nm. It is suggested that the two bands are the absorption of top-Si and bottom-Si0.8Ge0.2 layers, respectively. The spectra of Si bulk and Si0.8Ge0.2 layer were also measured to verify our results and relating mechanisms are explained here.
... Due to its relatively low resistivity (∼10 −6 m) and its good transmittance (∼80%) in the visible and near-infrared (NIR) ranges, ITO finds applications in optoelectronic devices, for instance as transparent electrodes for flat panels and solar cells [2]. It has recently also found application as a neutron detector [3]. The free electrons responsible for the relatively low resistivity come from oxygen vacancies, which donate electrons, and from the Sn doping. ...
Thin (6-320 nm) indium tin oxide films were deposited by pulsed excimer (XeCl) laser ablation. The lowest electrical resistivity (1.6×10-6 Ω m) was measured for samples deposited on moderately heated (200 °C) glass substrates. Optical transmissivity of the films in the range 400-1200 nm is higher than 80%. Ultra-thin (~6-9 nm) films were deposited and successfully used as transparent electrodes in optoelectronic devices.
Heat flux is key parameter for evaluating the heat dissipation of turbine blade. The accurate measurement of heat flux is vital for the optimizing cooling system and fabrication of turbine blade. The thin film heat flux gauge is usually fabricated on insulated substrate and located away from the measured area of turbine blade. As a result, the changes of heat flux on the surface of turbine blade cannot be reflected quickly and accurately. This paper innovatively designs membrane structure of thin film heat flux gauge on nickel alloys. The sensor is fabricated on the surface of the nickel alloys by thin-film depositing technology to realize in-situ surface heat flux measurement, and ITO/In
2
O
3
thermopile is used to replace precious thermopile to improve sensitivity. The results show that the sensitivity and response frequency of the sensor respectively are measured to be
/(kW/m
2
) and over 14400Hz respectively, which can measure heat flux of 236.4kW/m
2
at
. Besides, the thin film heat flux gauge is fabricated on the surface of turbine blade to verify functional feasibility with same preparation process of that on nickel alloys, and can obtain reproducible results. This work suggest that the thin film sensor based on ITO/In
2
O
3
thermopile has great potential in applications used as optimizing cooling system of components in aeronautics and astronautics.
Indium Tin Oxide (ITO) thin films were deposited on glass substrates with different film thickness. The influence of film thickness on the crystal structure of the films, transmittance, resistivity and surface morphology was investigated by optical transmission spectrum, four-point probe method, SEM and XRD. The experiment results showed that the films deposited in five minute had excellent electrical and optical property. The sheet resistance of ITO film was 17 Ω/□ and average transmittance of the film in visible region was 84%.
Indium-tin oxide is a ceramic material that exhibits electrical conductivity and optical transparency. It is used as transparent electrode in many optoelectronic devices. Among the possible deposition methods, magnetron sputtering is one of the most attractive techniques due to its good reproducibility and possibility of uniform deposition over large areas. In this work, indium-tin oxide thin films with different deposition times were obtained by radio frequency magnetron sputtering without intentional substrate heating. Their optical, electrical, physical and chemical properties were investigated.
Tin-doped indium oxide (ITO) thin films were deposited on glass substrates by direct current (DC) magnetron sputtering, using an ITO target with a combination of 90% In2O3 and 10% SnO2 in mass fraction. The effects of substrate temperature on the thin film's transparency and resistivity were studied by spectrophotometer and four-point probe meter. The structural was analyzed by X-ray diffraction (XRD) diffractometer. The interplanar spacing and crystal grain size were calculated, the mechenical properties of films were studied. The results showed that the lowest resistivity could be got while the transparency maintained above 85% with the proper substrate temperature of 200°C, that is to say there is an optimal substrate temperature to prepare the best performance thin film. It showed that the higher the substrate temperature became the better the crystallization was.
It has been proved by the World Health Organization (WHO) that electromagnetic waves would bring threats to public health in the tourism environment. However, most of the recent research about the relationship between building materials and electromagnetic waves was mainly focused on the electromagnetic products. It has also been claimed that the related research can rarely been found. Generally, ecotourism more tends to emphasize on a development of a new product and uni-environment study. However, these studies did not concern much on the application for conformity of healthcare living materials, particularly to those block high-transparency materials. Hence, this research approaches to conform the application of architectural technique for producing tin-based powder with the add-on of Ni and Mg, in order to discuss the fully anti-electromagnetic wave property of healthcare material. With a low-cost advantage, the application field of architecture defines the ternary powder system, namely Sn-Al-Ni (SAN) and Sn-Al-Mn (SAM). Additionally, the surface coating method can be implemented to review the influence of particle size, content ratio of Ni and Mn, stack effect, porosity and thickness to electromagnetic interference (EMI) mechanism.
Medical use quartz components for electromagnetic shielding materials research topics very rarely, therefore, intend to systematic development of coated quartz glass materials. The considerations for against electromagnetic waves (Electromagnetic Interference Shielding, EMI), one conductive coating film is required. The anti-high-frequency electromagnetic waves also need magnetic coating film. The thin film is translucent with a poor crystallinity, must be heat-treated to have good crystallization and conductivity, and therefore finds the feasible of Ni-based coating and interface effects also have the academic importance. This program is to deposit Ni-based thin film on different quartz planes (Ni/SiO2), and explores the effect of heat treatment on the structure. That contains crystalline characteristics (doping concentration: the Ni-base matrix doping Fe, 10at%~ 50at.%), optical properties and electrical conductivity. Finally, the electromagnetic shielding effect (EMI) of the coating structure is assessed. So, the application data for the characteristics of interface layer and anti-electromagnetic (EMI) properties are obtained. building materials extended to the health care system materials systems. The results show that Sn-40Al-xNi film increased the electromagnetic interference (EMI) shielding after annealed. For the Sn-40Al-10Ni films with higher Ni atomic concentration, the low frequency EMI shielding could be improved. For the sputtering films the annealed treatment not only had higher electric conductivity but also increased the high frequency EMI shielding.
SiO2 and ITO (indium tin oxide) were deposited by ablating
Si, SiO and ITO targets, respectively, in low- pressure oxygen
atmosphere with pulsed XeCl and KrF excimer laser. The SiO2
and ITO films were deposited on Si<100> and glass (BK7) substrates
at temperatures of 20-600 degree(s)C. The substrates were generally set
parallel to the target. To reduce droplet deposition in SiO2
films, the off-axis configuration or the so-called eclipse method,
characterized by a shadow mask between target and substrate were used.
Dense, continuous ITO films with resistivity as low as 1.6x10-4/
(Omega cm and a high transparency (80-90%) in the visible and
near-infrared regions were deposited. Ultra-thin (approximately 6 nm)
films were deposited and successfully used as electrodes in
optoelectronic devices. Dense, stoichiometric, thick (>2 micrometers
) SiO2 films were deposited on substrates either at room
temperature or heated at moderate temperatures (100- 600 degree(s)C).
Droplet density and surface roughness strongly depend on ablation
configuration. Roughness can be kept quite low (approximately 5 nm) by
using the KrF laser and a quite large target-to-substrate distance (8-12
cm). It is shown that multi-component films like ITO and Silica
(SiO2) can be efficiently deposited by using the reactive
pulsed laser deposition technique.
Nonalloyed transparent ohmic contacts of indium tin oxide (ITO) to p-type Si0.8Ge0.2 layer with and without a Si-capping layer were examined. The ITO films and the p-type Si0.8Ge0.2 layers were deposited by using sputtering and ultrahigh-vacuum chemical vapor deposition, respectively. It is shown that the ITO/p-type Si0.8Ge0.2 contact structure exhibits a specific contact resistance of 2.26×10−5 Ω cm2 as compared to that of 2.78×10−2 Ω cm2 for the ITO/Si/p-type Si0.8Ge0.2 contact structure. Possible mechanisms are proposed. The ITO film exhibits a transmittance more than 85% within a wavelength range from 800 to 1400 nm. Therefore, the ITO film has a high potential for fabricating near infrared optoelectronic devices using Si1−xGex material.
The laser-induced ablation threshold of indium oxide (In2O3) films was studied in order to evaluate the possibility of using this material as a photoresist for vacuum ultraviolet lithography.
In2O3 films with a thickness of about 30 nm were prepared by electron beam cathode sputtering with deposition onto quartz substrates
in a rarefied oxygen-containing atmosphere. Then the films were irradiated by 20-ns pulses of an ArF excimer laser operating
at a wavelength of λ=193 nm and a variable pulse intensity E
p. For a laser intensity below 30 mJ/cm2, the oxide etching rate is negligibly small. As the laser radiation intensity increases above this threshold, the etching
becomes more effective due to the development of a thermal ablation component.
Silicon detectors for alpha, gamma, neutron and fission fragment radiation spectrometry have been prepared, by applying low energy (3 and 5 keV) ion implantation techniques together with appropriate mechanical and chemical treatment. The spectrometric measurements were carried out at room temperature. The radiation stability of the detectors was checked in mixed gamma-neutron fields.
One- and two-dimensional position sensitive detectors based on an ITO - pSi structure have been fabricated and studied. The experimentally measured linear dependence between the photovoltage response and the light spot position is explained by a model in which the electric field in silicon in the lateral direction is assumed to be constant. It has been shown that is inversely proportional to the electron diffusion length. Using the experimental data the electron diffusion length is estimated to be about 1 cm.
The authors present a detailed analysis of the electrical and optical properties of amorphous transparent conducting thin films of indium oxide prepared by ion beam sputtering with a wide range of carrier concentrations. They show that the resistivity is dominated by ionised impurity scattering despite the amorphous structure of the films. The weak effect of the structural disorder is confirmed by studies of the interband absorption and is explained by a consideration of the relative length scales of the structural disorder and the Fermi wavelength.
Insulating films of In 2 O 3 were prepared by sputtering indium in the presence of pure oxygen using dc magnetron sputtering. Transmission electron microscopic investigations showed the films to be single phase and polycrystalline. Analysis of the optical transmittance data showed the films to have an optical band gap of 3.71±0.01 eV. Tunnel junctions were made with high T c superconductors Bi 2 Sr 2 Ca 1 Cu 2 O y and NdBa 2 Cu 3 O 7-δ using indium oxide as the barrier layer and Pb 0.5 In 0.5 as the counter electrode. The conductance spectra displayed prominent structures attributable to energy gap. The reduced gap parameters for Bi 2 Sr 2 Ca 1 Cu 2 O y and NdBa 2 Cu 3 O 7-δ were found to be 4.0±0.5 and 5.2±0.6, respectively.
Indium oxide films with an electrical resistivity of less than 1.5×10-4 Ω cm and good optical quality were prepared by the reactive ion plating of pure indium in an oxygen atmosphere of ∼10-4 Torr. The deposition rate was in the range of 500–900 Å/min, which is much higher than that of the ordinary evaporation. Hall effect measurement showed that the observed low resistivity is primarily due to the high electron mobility (≥70 cm2/V s) with carrier density up to 7×1020/cm3. These properties were correlated with the atomic concentration data by Auger electron spectroscopy and x‐ray photoelectron spectroscopy. It has been found that the films of low resistivity had the atomic ratio of O to In of 1.29–1.31.
Highly transparent (over 90% transmission in the visible range) and highly conductive (resistivity ≃2×10-4 Ω cm) indium oxide (undoped) films have been produced by thermal evaporation from an In+In 2 O 3 source in a vacuum chamber containing low pressures of O 2 . These properties are comparable or superior to the best tin‐doped indium oxide films ever reported, and excellent reproducibility has been achieved. Hall effect measurements have revealed that the observed low resistivity is primarily a result of the excellent electron mobility (≃70 cm2/V sec), although the electron concentration is also rather high (⩾4×1020/cm3). X‐ray diffraction measurements show distinctly polycrystalline In 2 O 3 structure with a lattice constant ranging from 10.07 to 10.11 Å. Electrolytic electroreflectance spectra exhibit at least four critical transitions, from which we have determined the direct and indirect optical band gaps (≃3.56 and 2.69 eV, respectively). Burstein shifts due to the population of electrons in the conduction band are also observed. These and other results along with a discussion of the processing details are reported.
High energy ion implantation of phosphorous and boron in the MeV-range has been applied to modify the vertical electric field distribution of silicon pn-junction radiation detectors. Low dose phosphorous implantation (10 MeV, 1011–1012 cm−2) was used to realize detectors with local high field regions characterized by an internal electric field strength up to 150 kV/cm. A field related decrease of the effective window down to 35 nm and a corresponding reduction of the pulse height defect (PHD) for the spectroscopy of low energy heavy ions have been obtained. Additional subjects for the application of the MeV-ion implantation technique are briefly summarized.
In this review paper we show that MIS (metal-insulator-semiconductor) and SIS (semiconductor-insulator-semiconductor) solar cells are basically one and the same type of device, even though they are usually regarded as being separate and are reported as such. Experimental results on the two most common systems, Al-SiO x -pSi and ITO-SiO x -pSi (ITO designates indium-tin-oxide) are presented to support a model where tunnel current through the insulator or interface is the transport mechanism between the metal or oxide semiconductor (acting as a collecting grid) and the base converting semiconductor. However, the I-V characteristics of the devices are dominated by diffusion current flow in the bulk of the base converting substrate and display the usual Shockley diode equation behavior, in the absence of additional defect current mechanisms.