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Wyszukujesz frazę "gallium" wg kryterium: Temat


Tytuł:
Gallium oxide buffer layers for gallium nitride epitaxy
Autorzy:
Korbutowicz, R
Wnek, J
Panachida, P
Serafinczuk, J
Srnanek, R
Powiązania:
https://bibliotekanauki.pl/articles/174303.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
hydride vapour phase epitaxy
gallium nitride
gallium oxide
thermal oxidation
buffer layer
Opis:
Gallium nitride (GaN) is very attractive semiconductor material because of its unique properties. The serious matter is a lack of easy access to bulk crystals of GaN. Synthesized crystals are precious and rather small. For these reasons almost all device manufacturers and researchers apply alternative substrates for gallium nitride devices epitaxy and it causes that the technology is intricate. Alternative substrates need buffer layers – their technology is usually complex and expensive. We have proposed a simple method to avoid large costs: applying gallium oxide – monoclinic β-Ga2O3, as the buffer layer, which has structural properties quite good matched to GaN. As the substrates made from single crystal gallium oxide are still hardly available on the market, we have used hydride vapour phase epitaxy (HVPE) GaN epilayers as a starting material. It can be GaN layer under good quality – middle or low. The oxidation process converts top GaN to β-Ga2O3 layer which can release or absorb the strain. Applying such structure in another, second, epitaxy of GaN allows to obtain good quality epitaxial structures using HVPE technique.
Źródło:
Optica Applicata; 2013, 43, 1; 73-79
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of p-type contacts to InGaN-based laser diodes and light emitting diodes grown by plasma assisted molecular beam epitaxy
Autorzy:
Nowakowski-Szkudlarek, Krzesimir
Muziol, Grzegorz
Żak, Mikolaj
Hajdel, Mateusz
Siekacz, Marcin
Feduniewicz-Żmuda, Anna
Skierbiszewski, Czesław
Powiązania:
https://bibliotekanauki.pl/articles/173471.pdf
Data publikacji:
2020
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
gallium nitride
molecular beam epitaxy
contacts
Opis:
We investigated the influence of the In0.17Ga0.83N:Mg contact layer grown by plasma assisted molecular beam epitaxy on the resistivity of p-type Ni/Au contacts. We demonstrate that the Schottky barrier width for p-type contact is less than 5 nm. We compare circular transmission line measurements with a p-n diode current-voltage characteristics and show that discrepancies between these two methods can occur if surface quality is deteriorated. It is found that the most efficient contacts to p-type material consist of In0.17Ga0.83N:Mg contact layer with Mg doping levelas high as 2 × 1020 cm–3.
Źródło:
Optica Applicata; 2020, 50, 2; 323-330
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Beneficiation of Ga from alunite concentrates by selective acid leaching and alkaline precipitation
Autorzy:
Zhu, Mao-Lan
Chen, Hang
Zhong, Shui-Ping
Huang, Zhong-Sheng
Chen, Xi
Hu, Zhi-Biao
Powiązania:
https://bibliotekanauki.pl/articles/110733.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
gallium
selective leaching
precipitation
alunite concentrate
Opis:
In this study beneficiation of Ga from alunite ore was investigated. The effects of the calcination temperature, H2SO4 concentration, leaching temperature and liquid-solid ratio on the dissolution characteristic of Ga, K and Al were studied. The results showed that increasing the calcination temperature, H2SO4 concentration and leaching temperature can improve the solubility of K and Al. However, higher H2SO4 concentration and lower leaching temperature can improve the dissolution of Ga, which was beneficial to recovery of Ga. On the basis of the solubility difference in H2SO4, a two-stage process of selective acid leaching and alkali precipitation of Ga was proposed. The concentration of Ga was increased significantly from 54 g/t in alunite ore to 4100 g/t in alkali precipitation product. The major elements of Al and K in alunite were recovered as the alum crystal with a purity of 99.62%.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 4; 1028-1038
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of changes in the resistivity of semi-insulating materials
Autorzy:
Suproniuk, Marek
Powiązania:
https://bibliotekanauki.pl/articles/1849000.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
resistivity
semiconductor
gallium phosphide
silicon carbide
Opis:
Electrical properties of semiconductor materials depend on their defect structure. Point defects, impurities or admixture contained in a semiconductor material, strongly affect its properties and determine the performance parameters of devices made on its basis. The results of the currently used methods of examining the defect structure of semiconductor material are imprecise due to solution of ill-posed equations. These methods do not allow for determination of concentration of the defect centers examined. Improving the resolution of the obtained parameters of defect centers, determining their concentration and studying changes in the resistivity of semi-insulating materials can be carried out, among others, by modelling changes in the concentration of carriers in the conduction and valence bands. This method allows to determine how charge compensation in the material affects the changes in its resistivity. Calculations based on the Fermi-Dirac statistics can complement the experiment and serve as a prediction tool for identifying and characterizing defect centers. Using the material models (GaP, 4H-SiC) presented in the article, it is possible to calculate their resistivity for various concentrations of defect centers in the temperature range assumed by the experimenter. The models of semi-insulating materials presented in the article were built on the basis of results of testing parameters of defect centers with high-resolution photoinduced transient spectroscopy (HRPITS). The current research will allow the use of modelling to determine optimal parameters of semi-insulating semiconductor materials for use in photoconductive semiconductor switches (PCSS).
Źródło:
Metrology and Measurement Systems; 2021, 28, 3; 581-592
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of changes in the resistivity of semi-insulating materials
Autorzy:
Suproniuk, Marek
Powiązania:
https://bibliotekanauki.pl/articles/1849019.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
resistivity
semiconductor
gallium phosphide
silicon carbide
Opis:
Electrical properties of semiconductor materials depend on their defect structure. Point defects, impurities or admixture contained in a semiconductor material, strongly affect its properties and determine the performance parameters of devices made on its basis. The results of the currently used methods of examining the defect structure of semiconductor material are imprecise due to solution of ill-posed equations. These methods do not allow for determination of concentration of the defect centers examined. Improving the resolution of the obtained parameters of defect centers, determining their concentration and studying changes in the resistivity of semi-insulating materials can be carried out, among others, by modelling changes in the concentration of carriers in the conduction and valence bands. This method allows to determine how charge compensation in the material affects the changes in its resistivity. Calculations based on the Fermi-Dirac statistics can complement the experiment and serve as a prediction tool for identifying and characterizing defect centers. Using the material models (GaP, 4H-SiC) presented in the article, it is possible to calculate their resistivity for various concentrations of defect centers in the temperature range assumed by the experimenter. The models of semi-insulating materials presented in the article were built on the basis of results of testing parameters of defect centers with high-resolution photoinduced transient spectroscopy (HRPITS). The current research will allow the use of modelling to determine optimal parameters of semi-insulating semiconductor materials for use in photoconductive semiconductor switches (PCSS).
Źródło:
Metrology and Measurement Systems; 2021, 28, 3; 581-592
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling of changes in the resistivity of semi-insulating materials
Autorzy:
Suproniuk, Marek
Powiązania:
https://bibliotekanauki.pl/articles/1849057.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
resistivity
semiconductor
gallium phosphide
silicon carbide
Opis:
Electrical properties of semiconductor materials depend on their defect structure. Point defects, impurities or admixture contained in a semiconductor material, strongly affect its properties and determine the performance parameters of devices made on its basis. The results of the currently used methods of examining the defect structure of semiconductor material are imprecise due to solution of ill-posed equations. These methods do not allow for determination of concentration of the defect centers examined. Improving the resolution of the obtained parameters of defect centers, determining their concentration and studying changes in the resistivity of semi-insulating materials can be carried out, among others, by modelling changes in the concentration of carriers in the conduction and valence bands. This method allows to determine how charge compensation in the material affects the changes in its resistivity. Calculations based on the Fermi-Dirac statistics can complement the experiment and serve as a prediction tool for identifying and characterizing defect centers. Using the material models (GaP, 4H–SiC) presented in the article, it is possible to calculatetheir resistivity for various concentrations of defect centers in the temperature range assumed by the experimenter. The models of semi-insulating materials presented in the article were built on the basis of results of testing parameters of defect centers with high-resolution photoinduced transient spectroscopy (HRPITS). The current research will allow the use of modelling to determine optimal parameters of semi-insulating semiconductor materials for use in photoconductive semiconductor switches (PCSS).
Źródło:
Metrology and Measurement Systems; 2021, 28, 3; 581-592
0860-8229
Pojawia się w:
Metrology and Measurement Systems
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cyclotron production of 68Ga via proton-induced reaction on 68Zn target
Autorzy:
Sadeghi, M.
Kakavand, T.
Rajabifar, S.
Mokhtari, L.
Rahimi-Nezhad, A.
Powiązania:
https://bibliotekanauki.pl/articles/146448.pdf
Data publikacji:
2009
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
production
gallium-68
zinc-68
PET
cyclotron
Opis:
68Ga is an important positron-emitting radionuclide for positron emission tomography. In this work 68Ga was produced via the 68Zn(p,n)68Ga nuclear reaction. 68Zn electrodeposition on a copper substrate was carried out by alkaline cyanide baths. 68Zn target was irradiated with a 15 MeV proton beam and a 150 mi A current. The production yield achieved was 136 mCi/ mi Aźh (5.032 GBq/mi Aźh). 68Ga was separated from zinc and copper by a combination of cation exchange chromatography and liquid-liquid extraction methods.
Źródło:
Nukleonika; 2009, 54, 1; 25-28
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Desorption of Argon Implanted into Gallium Arsenide
Autorzy:
Turek, Marcin
Droździel, Andrzej
Pyszniak, Krzysztof
Węgierek, Paweł
Powiązania:
https://bibliotekanauki.pl/articles/2201837.pdf
Data publikacji:
2022
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
thermal desorption spectroscopy
gallium arsenide
ion implantation
Opis:
Thermal desorption of Ar implanted with energies 150 keV and 100 keV with fluence 1×10^16 cm^-2 into GaAs is considered. A sudden release of Ar is observed in temperature range 1100 -1180 K as a single narrow peak in TDS (Thermal Desorption Spectroscopy) spectra. This is accompanied by a strong background signal from atmospheric Ar trapped in various parts of the spectrometer. Desorption peak shift analysis allows estimation of desorption activation energy values - these are 3.6 eV and 2.5 eV for implantation energies 150 keV and 100 keV, respectively. These results are comparable to that measured for Ar implanted into germanium target.
Źródło:
Advances in Science and Technology. Research Journal; 2022, 16, 4; 318--326
2299-8624
Pojawia się w:
Advances in Science and Technology. Research Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Production and quality control of 66Ga radionuclide
Autorzy:
Sabet, M.
Rowshanfarzad, P.
Jalilian, A.
Ensaf, M.
Rajamand, A.
Powiązania:
https://bibliotekanauki.pl/articles/146278.pdf
Data publikacji:
2006
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
gallium-66
cyclotron
radiochemical separation
target recovery
Opis:
The purpose of this study was to develop the required targetry and radiochemical methods for production of 66Ga, according to its increasing applications in various fields of science. The 66Zn(p,n)66Ga reaction was selected as the best choice for the production of 66Ga. The targets were bombarded with 15 MeV protons from cyclotron (IBA-Cyclone 30) at the Nuclear Research Center for Agriculture and Medicine (NRCAM) with a current of 180 mA for 67 min. ALICE and SRIM (Stopping and Range of Ions in Matter) nuclear codes were used to predict the optimum energy and target thickness. Targets were prepared by electroplating 95.73% enriched 66Zn on a copper backing. Chemical processing was performed by a no-carrier-added method consisting of ion exchange chromatography and liquid-liquid extraction. Anion exchange chromatography was also used for the recovery of target material. Quality control of the product was carried out in two steps of chemical and radionuclide purity control. The activity of 66Ga was 82.12 GBq at EOB and the production yield was 410.6 MBq/mAh. The radiochemical separation yield was 93% and the yield of chemical recovery of the target material was 97%. Quality control tests showed a radionuclide purity higher than 97% and the amounts of chemical impurities were in accordance with the United States Pharmacopoeiae levels.
Źródło:
Nukleonika; 2006, 51, 3; 147-154
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Calorimetric Measurements of Ga-Li System by Direct Reaction Method
Autorzy:
Dębski, A.
Powiązania:
https://bibliotekanauki.pl/articles/350810.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gallium-lithium system
Ga-Li
calorimetry
thermochemistry
Opis:
The direct reaction calorimetric method was used for the determination of the formation enthalpy of alloys which concentrations correspond to the: Ga7Li2, Ga9Li5, GaLi, Ga4Li5, Ga2Li3, and GaLi2 intermetallic phases. The obtained experimental values of the formation enthalpy were: –18.1 ±0.8 kJ/mol at., –26.5 ±0.3 kJ/mol at., –34.7 ±0.3 kJ/mol at., –33.5 ±0.5 kJ/mol at., –32.8 ±0.3 kJ/mol at. and –24.6 ±1.4 kJ/mol at., respectively. After the calorimetric measurements, all the samples were checked by way of X-ray diffraction investigations to confirm the structure of the measured alloys. All the measured values of the formation enthalpy of the Ga-Li alloys were compared with literature data and the data calculated with use of the Miedema model.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2A; 919-926
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and evaluation of a [66Ga]gallium chitosan complex in fibrosarcoma bearing animal models
Autorzy:
Pourjavadi, A.
Akhlaghi, M.
Jalilian, A. R.
Powiązania:
https://bibliotekanauki.pl/articles/147067.pdf
Data publikacji:
2011
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
chitosan
gallium-66
internal radiotherapy
fibrosarcoma
intratumoral injection
Opis:
[66Ga]gallium chitosan complex was prepared with a high radiochemical purity (greater than 99%) in dilute acetic acid solution. The radiochemical purity of [66Ga]gallium chitosan complex was checked by using paper chromatography technique. The prepared complex solution was injected intratumoral to fibrosarcoma-bearing mice and the leakage of radioactivity from injection site was investigated. Approximately, 85.4% of the injected dose was retained in the injection site 54 h after injection and most of the leaked radioactivity was accumulated in the blood, liver (0.5%) and lung (6.5%).
Źródło:
Nukleonika; 2011, 56, 1; 35-40
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Biosorption Performance of Biodegradable Polymer Powders for the Removal of Gallium(III) ions from Aqueous Solution
Autorzy:
Lee, Ching-Hwa
Lin, Hang-Yi
Cadogan, Elon I.
Popuri, Srinivasa R.
Chang, Chia-Yuan
Powiązania:
https://bibliotekanauki.pl/articles/778539.pdf
Data publikacji:
2015
Wydawca:
Zachodniopomorski Uniwersytet Technologiczny w Szczecinie. Wydawnictwo Uczelniane ZUT w Szczecinie
Tematy:
chitosan
crab shell powder
gallium
Langmuir-Freundlich
kinetics
Opis:
Gallium (Ga) is considered an important element in the semiconducting industry and as the lifespan of electronic products decrease annually Ga-containing effluent has been increasing. The present study investigated the use of biodegradable polymer powders, crab shell and chitosan, in the removal of Ga(III) ions from aqueous solution. Ga(III) biosorption was modeled to Lagergren-first, pseudo-second order and the Weber-Morris models. Equilibrium data was modeled to the Langmuir, Freundlich and Langmuir-Freundlich adsorption isotherms to determine the probable biosorption behavior of Ga(III) with the biosorbents. The biosorbents were investigated by Fourier Transform Infrared Spectroscopy, X-ray Diffraction and Scanning Electron Microscopy/Energy Dispersive Spectra analysis.
Źródło:
Polish Journal of Chemical Technology; 2015, 17, 3; 124-132
1509-8117
1899-4741
Pojawia się w:
Polish Journal of Chemical Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Uranium and neodymium partitioning in alkali chloride melts using low-melting gallium-based alloys
Autorzy:
Melchakov, S. Y.
Maltsev, D. S.
Volkovich, V. A.
Yamshchikov, L. F.
Lisienko, D. G.
Osipenko, A. G.
Rusakov, M. A.
Powiązania:
https://bibliotekanauki.pl/articles/146407.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
neodymium
uranium
gallium
separation factor
reductive extraction
pyrochemical reprocessing
Opis:
Partitioning of uranium and neodymium was studied in a ‘molten chloride salt – liquid Ga-X (X = In or Sn) alloy’ system. Chloride melts were based on the low-melting ternary LiCl-KCl-CsCl eutectic. Nd/U separation factors were calculated from the thermodynamic data as well as determined experimentally. Separation of uranium and neodymium was studied using reductive extraction with neodymium acting as a reducing agent. Efficient partitioning of lanthanides (Nd) and actinides (U), simulating fission products and fissile materials in irradiated nuclear fuels, was achieved in a single stage process. The experimentally observed Nd/U separation factor valued up to 106, depending on the conditions.
Źródło:
Nukleonika; 2015, 60, No. 4, part 2; 915-920
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Behavior of gallium and germanium associated with zinc sulfide concentrate in oxygen pressure leaching
Autorzy:
Liu, F.
Liu, Z.
Li, Y.
Wilson, B. P.
Lundstrom, M.
Powiązania:
https://bibliotekanauki.pl/articles/110812.pdf
Data publikacji:
2017
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
zinc sulfide concentrate
gallium
germanium
pyrite
oxygen pressure leaching
Opis:
The Fankou zinc concentrate (Guangdong province, China) was mineralogically characterized and results showed that the main germanium-bearing minerals in the sample comprised of zinc sulfide and galena, whereas gallium-bearing minerals were pyrite, sphalerite and silicate. Oxygen pressure leaching of zinc sulfide concentrate was carried out in order to investigate the effect of pressure, leaching time, sulfuric acid and copper concentrations on the leaching behavior of gallium and germanium. Under optimum conditions, leaching of Zn, Fe, Ge and Ga reached 98.21, 90.45, 97.45 and 96.65%, respectively. In the leach residues, it was determined that some new precipitates, such as PbSO4, CaSO4 and SiO2, were formed, which co-precipitated a certain amount of Ga and Ge from the leach solution. The results clearly indicated that Ga and Ge were much more difficult to leach than Zn, and provided answers to why the leaching efficiency of Ga is 10% lower when compared to Ge.
Źródło:
Physicochemical Problems of Mineral Processing; 2017, 53, 2; 1047-1060
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of photoconductive semiconductor switch parameters with selected switch devices in power systems
Autorzy:
Piwowarski, Karol
Powiązania:
https://bibliotekanauki.pl/articles/1818252.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
electronic devices
electric switch
photoconductive semiconductor switches
gallium phosphide
Opis:
Currently, work is underway to manufacture and find potential applications for a photoconductive semiconductor switch made of a semi-insulating material. The article analyzes the literature in terms of parameters and possibilities of using PCSS switches, as well as currently used switches in power and pulse power electronic system. The results of laboratory tests for the prototype model of the GaP-based switch were presented and compared with the PCSS switch parameters from the literature. The operating principle, parameters and application of IGBT transistor, thyristor, opto-thyristor, spark gap and power switch were presented and discussed. An analysis of the possibilities of replacing selected elements by the PCSS switch was carried out, taking into account the pros and cons of the compared devices. The possibility of using the currently made PCSS switch from gallium phosphide was also discussed.
Źródło:
Opto-Electronics Review; 2020, 28, 2; 74--81
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Comparison of photoconductive semiconductor switch parameters with selected switch devices in power systems
Autorzy:
Piwowarski, K.
Powiązania:
https://bibliotekanauki.pl/articles/1818254.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Stowarzyszenie Elektryków Polskich
Tematy:
electronic devices
electric switch
photoconductive semiconductor switches
gallium phosphide
Opis:
Currently, work is underway to manufacture and find potential applications for a photoconductive semiconductor switch made of a semi-insulating material. The article analyzes the literature in terms of parameters and possibilities of using PCSS switches, as well as currently used switches in power and pulse power electronic system. The results of laboratory tests for the prototype model of the GaP-based switch were presented and compared with the PCSS switch parameters from the literature. The operating principle, parameters and application of IGBT transistor, thyristor, opto-thyristor, spark gap and power switch were presented and discussed. An analysis of the possibilities of replacing selected elements by the PCSS switch was carried out, taking into account the pros and cons of the compared devices. The possibility of using the currently made PCSS switch from gallium phosphide was also discussed.
Źródło:
Opto-Electronics Review; 2020, 28, 2; 74--81
1230-3402
Pojawia się w:
Opto-Electronics Review
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simple, responsive and cost effective simultaneous quantification of Ga(III) and In(III) in environmental water samples
Autorzy:
Grabarczyk, M.
Adamczyk, M.
Powiązania:
https://bibliotekanauki.pl/articles/2082480.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
gallium(III)
indium(III)
trace analysis
environmental
water samples
Opis:
The simultaneous determination of Ga(III) and In(III) in environmental water samples was described. The procedure was based on adsorptive stripping voltammetry using an in situ plated bismuth film electrode as a working electrode. In order to obtain low detection limits and satisfactory separations of gallium and indium peaks on the voltammogram, cupferron was used as a complexing agent. The optimum composition of the supporting electrolyte was found to be: 0.1 mol l-1 acetate buffer (pH=5.0), 2 × 10-4 mol l-1 cupferron, 2 × 10-4 mol l-1 Bi(III), optimal voltammetric parameters were found to be: accumulation potential -0.9 V, accumulation time 60 s. The linear range of Ga(III) as well as In(III) was observed over a concentration range from 2.5 × 10-8 mol l-1 to 1.5 × 10-6 mol l-1. The method was satisfactorily applied to the simultaneous quantification of gallium and indium in environmental water samples. This facilitated a promising application of the recommended procedure for monitoring the environment, which is necessary to evaluate the soil-plant system.
Źródło:
International Agrophysics; 2019, 33, 2; 161-166
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Active Damping in Series Connected Power Modules with Continuous Output Voltage
Autorzy:
Ulmer, Sabrina
Schullerus, Gernot
Sönmez, Ertugrul
Powiązania:
https://bibliotekanauki.pl/articles/1955969.pdf
Data publikacji:
2021
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
power electronics
modularity
scalability
GaN
gallium nitride
active filter damping
Opis:
This paper presents a modular and scalable power electronics concept for motor control with continuous output voltage. In contrast to multilevel concepts, modules with continuous output voltage are connected in series. The continuous output voltage of each module is obtained by using gallium nitride (GaN) high electron motility transistor (HEMT)s as switches inside the modules with a switching frequency in the range between 500 kHz and 1 MHz. Due to this high switching frequency a LC filter is integrated into the module resulting in a continuous output voltage. A main topic of the paper is the active damping of this LC output filter for each module and the analysis of the series connection of the damping behaviour. The results are illustrated with simulations and measurements.
Źródło:
Power Electronics and Drives; 2021, 6, 41; 314-335
2451-0262
2543-4292
Pojawia się w:
Power Electronics and Drives
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zintegrowany proces otrzymywania monokryształów SI GaAs metodą Czochralskiego z hermetyzacją cieczową
Integrated process of SI GaAs crystals manufacturing by the Liquid Encapsulated Czochralski method
Autorzy:
Hruban, A.
Orłowski, W.
Mirowska, A.
Strzelecka, S.
Piersa, M.
Jurkiewicz-Wegner, E.
Materna, A.
Dalecki, W.
Powiązania:
https://bibliotekanauki.pl/articles/192082.pdf
Data publikacji:
2012
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Technologii Materiałów Elektronicznych
Tematy:
SI GaAs
obróbka termiczna
EPD
gallium arsenide
LEC thermal annealing
Opis:
Standardowa technologia otrzymywania półizolujących monokryształów SI GaAs składa się z 3 etapów tzn. syntezy, monokrystalizacji i obróbki termicznej, która jest niezbędna dla uzyskania rezystywności ρ ≥ 107 Ohmcm i ruchliwości nośników ładunku μ ≥ 5000 cm2/Vs. Synteza i monokrystalizacja są wykonywane w ramach jednego procesu w wysokociśnieniowym urządzeniu Czochralskiego. Standardowa obróbka termiczna jest procesem osobnym polegającym na wygrzewaniu kryształów w zamkniętych ampułach kwarcowych w atmosferze par As. Proces ten jest pracochłonny, wymaga dodatkowych urządzeń oraz zwiększa koszty. Przedmiotem pracy było uproszczenie technologii wytwarzania monokryształów SI GaAs przez obróbkę cieplną zintegrowaną z procesami syntezy i monokrystalizacji. Przeprowadzono zintegrowane procesy monokrystalizacji i wygrzewania otrzymując monokryształy o średnicach 2" i 3" i ciężarze ~ 3 kg. Własności takich kryształów porównano z monokryształami wytwarzanymi w procesach standardowych. Wykazano, że właściwości fizyczne takie jak: rezystywność, ruchliwość i gęstość dyslokacji nie zależą od sposobu prowadzenia procesu (standardowy, zintegrowany) lecz są tylko funkcją temperatury wygrzewania. Proces zintegrowany upraszcza technologię wytwarzania, a jednocześnie obniża poziom stresów termicznych eliminując pękanie kryształów.
A standard technological process of manufacturing SI GaAs single crystals consists of 3 steps, namely synthesis, crystal growth and thermal annealing, which are necessary to reach high resistivity (ρ ≥ 107 Ohmcm) and high carrier mobility (μ ≥ 5000 cm2/Vs). Usually both synthesis and crystal growth are realized in one process in a high pressure Czochralski puller. The thermal annealing process is carried out in a sealed quartz ampoule under arsenic (As) vapor pressure. This increases the costs of the process due to a need for the equipment and, in addition, is time consuming. The subject matter of this work was the improvement of the SI GaAs technology by integrating the thermal annealing step with synthesis and crystal growth. The integrated manufacturing processes of SI GaAs crystals with 2" and 3" in diameter and ~ 3000 g in weight were performed. Their physical properties were compared with these of the crystals obtained in a standard process. Preliminary results of this work indicate that it is possible to improve the SI GaAs technology and decrease the manufacturing costs. They also prove that thermal stress in the crystals can be decreased, as a result of which cracks will not appear during the mechanical treatment (cutting, lapping).
Źródło:
Materiały Elektroniczne; 2012, T. 40, nr 3, 3; 38-47
0209-0058
Pojawia się w:
Materiały Elektroniczne
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of [66Ga]oxine complex; a possible PET tracer
Autorzy:
Jalilian, A.
Rowshanfarzad, P.
Sabet, M.
Rahiminejad-Kisomi, A.
Rajamand, A.
Powiązania:
https://bibliotekanauki.pl/articles/146276.pdf
Data publikacji:
2006
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
gallium-66
oxine
positron emission tomography
blood cell labeling
stability
Opis:
The aim of this work is development of a possible blood cell labeling agent for ultimate use in PET. Gallium-66 (T1/2 = 9.49 h) is an interesting radionuclide that has a potential for positron emission tomography (PET) imaging of biological processes with intermediate to slow target tissue uptake. Oxine has been labeled with this radionuclide in the form of [66Ga]gallium chloride for its possible diagnostic properties. In this study, 66Ga was produced at a 30 MeV cyclotron (IBA-Cyclone 30) via the 66Zn(p,n)66Ga reaction. The production yield was 445.5 MBq/mAh. The [66Ga]oxine complex was obtained at pH = 5 in phosphate buffer medium at 37°C in 10 min. Radio-TLC showed a radiochemical purity of more than 98 š 2%. The chemical stability of the complex was checked in vitro with a specific activity of 1113 GBq/mmol. The serum stability and log P of the complex were calculated. The produced [66Ga]oxine can be used for diagnostic studies, due to its desirable physico-chemical properties both in vitro and in vivo according to internationally accepted limits.
Źródło:
Nukleonika; 2006, 51, 3; 155-159
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modelling and Simulation of Normally-Off AlGaN/GaN MOS-HEMTs
Autorzy:
Taube, A.
Sochacki, M.
Szmidt, J.
Kamińska, E.
Piotrowska, A.
Powiązania:
https://bibliotekanauki.pl/articles/226802.pdf
Data publikacji:
2014
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
gallium nitride
MOS-HEMT
high electron mobility
transistor
AlGaN
GaN
simulation
Opis:
The article presents the results of modelling and simulation of normally-off AlGaN/GaN MOS-HEMT transistors. The effect of the resistivity of the GaN:C layer, the channel mobility and the use of high-κ dielectrics on the electrical characteristics of the transistor has been examined. It has been shown that a low leakage current of less than 10⁻⁶ A/mm can be achieved for the acceptor dopant concentration at the level of 5×10¹⁵cm⁻³. The limitation of the maximum on-state current due to the low carrier channel mobility has been shown. It has also been demonstrated that the use of HfO₂, instead of SiO₂, as a gate dielectric increases on-state current above 0.7A/mm and reduces the negative influence of the charge accumulated in the dielectric layer.
Źródło:
International Journal of Electronics and Telecommunications; 2014, 60, 3; 253-258
2300-1933
Pojawia się w:
International Journal of Electronics and Telecommunications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recycling of Gallium from End-of-Life Light Emitting Diodes
Autorzy:
Nagy, S.
Bokányi, L.
Gombkötő, I.
Magyar, T.
Powiązania:
https://bibliotekanauki.pl/articles/356762.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
LED
LED recycling
LED chip
gallium
mechanical enrichment
mechanochemical activation
leaching
Opis:
Nowadays Light Emitting Diodes (LEDs) are widely utilized. They are applied as backlighting in Liquid Crystal Displays (LCD) and TV sets or as lighting equipments in homes, cars, instruments and street-lightning. End of life equipments are containing more and more LEDs. The recovery of valuable materials – such as Ga, Au, Cu etc. – from the LEDs is essential for the creating the circular economy. First task is the development of a proper recycling technology. Most of the researchers propose fully chemical or thermal-chemical pathway for the recycling of LEDs. In the meantime our approach based on the thorough investigation of the structure and composition of LEDs, and shown in this paper, is the combination of mechanical and chemical techniques in order to recover more valuable products, as well as to facilitate the mass transfer. Our laboratory scale experiments are introduced, the final aim of which is Ga recovery in accordance with our above approach. It was experimentally proved that the LED chips contain Ga and can be recovered by mechanical processes along with copper-product. Ga is presented on the surface of the chips in GaN form. Mechano-chemical activation in high energy density stirred medium mill and the following acidic leaching resulted in the enrichment of 99.52% of gallium in the pregnant solution.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1161-1166
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation and primary evaluation of 66Ga-DTPA-chitosan in fibrosarcoma bearing mice
Autorzy:
Akhlaghi, M.
Pourjavadi, A.
Powiązania:
https://bibliotekanauki.pl/articles/147065.pdf
Data publikacji:
2011
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
DTPA-chitosan
degree of modification (DM)
gallium-66
radiolabeled
intratumoral injection
Opis:
Chitosan was chemically modified by diethylenetetraaminepentaacetic acid (DTPA) in different degrees of modification (DM = 6.1, 10.3, 15.7 and 20.9%). DTPA-chitosans were radiolabeled with gallium-66 radionuclide. The effect of several factors on labeling yield such as degree of modification, acidity and concentration of DTPA-chitosan solution, contact time and radioactivity was investigated. Radiolabeled DTPA chitosans were intratumorally injected to fibrosarcoma bearing mice and the leakage of radioactivity from the injection site was evaluated. In comparison with chitosan, all DTPA chitosans showed better efficiency in preventing the leakage of radioactivity from tumor lesion and DTPA-chitosan (DM = 10.3%) was the best which led to remaining 97% of injected dose in the injection site after 54 h of injection. The highest leaked radioactivity from the injection site was in the lungs, liver, spleen and the kidneys. Our results indicated that the DTPA modified chitosan can be an effective carrier for therapeutic radionuclides for tumor treatment by the intratumoral injection technique.
Źródło:
Nukleonika; 2011, 56, 1; 41-47
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Two-dimensional modeling of surface photovoltage in metal/insulator/n-GaN structure with cylindrical symmetry
Autorzy:
Matys, M
Powroznik, P
Kupka, D
Adamowicz, B
Powiązania:
https://bibliotekanauki.pl/articles/174326.pdf
Data publikacji:
2013
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
surface photovoltage
gallium nitride
metal-insulator-semiconductor (MIS) structure
interface states
photodetector
Opis:
The rigorous numerical analysis of the surface photovoltage (SPV) versus excitation UV-light intensity (Φ), from 104 to 1020 photon/(cm2s) in a metal/insulator/n-GaN structure with a negative gate voltage (VG = –2 V) was performed using a finite element method. In the simulations we assumed a continuous U-shape density distribution function Dit(E) of the interface states and n-type doping concentration ND = 1016 cm–3. The SPV signal was calculated and compared in three different characteristic regions at the interface, namely i) under the gate centre, ii) near the gate edge and iii) between the gate and ohmic contact. We attributed the differences in SPV(Φ) dependences to the influence of the interface states in terms of the initial band bending and interface recombination controlled by the gate bias. The obtained results are useful for the design of GaN-based UV-radiation photodetectors.
Źródło:
Optica Applicata; 2013, 43, 1; 47-52
0078-5466
1899-7015
Pojawia się w:
Optica Applicata
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Application of poly-energy implantation with H+ ions for additional energy levels formation in GaAs dedicated to photovoltaic cells
Autorzy:
Węgierek, Paweł
Pietraszek, Justyna
Powiązania:
https://bibliotekanauki.pl/articles/141449.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
energy levels
gallium arsenide
intermediate band solar cells
ion implantation
thermal admittance spectroscopy
Opis:
: The aim of this article is to present the results of research aimed at confirmation whether it is possible to form an intermediate band in GaAs implantation with H+ ions. The obtained results were discussed with particular emphasis on possible applications in the photovoltaic industry. As it is commonly known, the idea of intermediate band solar cells reveals considerable potential as the most fundamental principle of the next generation of semiconductors solar cells. In progress of the research, a series of GaAs samples were subjected to poly-energy implantation of H+ ions, followed by high-temperature annealing. Tests were conducted using thermal admittance spectroscopy, under conditions of variable ambient temperature, measuring signal frequency in order to localize deep energy levels, introduced by ion implantation. Activation energy ∆E was determined for additional energy levels resulting from the implantation of H+ ions. The method of determining the activation energy value is shown in Fig. 2 and the values read from it are σ0 = 10−9 (Ω·cm)−1 for 1000/T0 = 3.75 K−1 and σ1 = 1.34 × 10−4 (Ω·cm)−1 for 1000/T1 = 2.0 K−1 . As a result, we obtain ∆E ≈ 0.58 eV. It was possible to identify a single deep level in the sample of GaAs implanted with H+ ions. Subsequently, its location in the band gap was determined by estimating the value of ∆E. However, in order to confirm whether the intermediate band was actually formed, it is necessary to perform further analyses. In particular, it is necessary to implement a new analytical model, which takes into consideration the phenomena associated with the thermally activated mechanisms of carrier transport as it was described in [13]. Moreover, the influence of certain parameters of ion implantation, post-implantation treatment and testing conditions should also be considered.
Źródło:
Archives of Electrical Engineering; 2019, 68, 4; 925-931
1427-4221
2300-2506
Pojawia się w:
Archives of Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł

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