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EN
Recently it has been found that the heterostructures of n-ZnO/p-Si are promising photovoltaic alternatives to silicon homojunctions. It is well known that the energy band diagram of a heterostructure is crucial for the understanding of its operation. This paper analyzes the ZnO/p-Si heterostructure band by using free AMPS-1D computer program simulations. The obtained numerical results are compared with theoretical calculations based on the depletion region approximation model and the Poisson’s equation for electric potential. The results of the simulation are also compared with the experimental C-V characteristics of the test n-ZnO/p-Si heterostructure. The simulated C-V characteristics is qualitatively consistent with the experimental C-V curve, which confirms the correctness of the determined band diagram of the n-ZnO/p-Si heterostructure.
EN
Electric vehicles (EV) have brought promising technologies for future mobility solutions. As one of the key components of EVs, battery systems have fundamental functions which disconnect the battery during parking and in case of failure. To provide a safe system, specialized high voltage (HV) electromechanical switches are used to perform these major functions such as switch on, switch off or pre-charging. Due to these components can be easily damaged, expensive, heavy and bulky, a solution based on pure semiconductors may be desired to accomplish these operations. Many studies were exhibited on EV battery systems regarding developing solid-state systems for HV switchgear. Developing technology on semiconductor devices allows to make a safety concept based on only solid-state components. This study presents a comprehensive analysis of pre-charge sequences between conventional and semiconductor switchgear to be used in electric vehicle battery systems. Spice simulations are presented to investigate advantages and drawbacks of these systems.
3
Content available remote Bezpieczniki szybkie do ochrony komponentów półprzewodnikowych
PL
Wraz z gwałtownym rozwojem energoelektroniki, zapoczątkowanym w latach 50. ubiegłego wieku, nastąpił rozwój różnych odmian półprzewodnikowych przyrządów mocy. Elementy te (np. diody, tyrystory, tranzystory mocy) cechują się słabymi parametrami przeciążeniowymi, dlatego wymagają bardzo wrażliwej i szybko działającej ochrony. Błędy skutkujące zwarciami w urządzeniach energoelektronicznych mogą spowodować niemałe uszkodzenia zarówno samego urządzenia, jak i jego otoczenia z uwagi na ryzyko eksplozji. Optymalnym rozwiązaniem w tym przypadku stają się bezpieczniki szybkie, specyficznie zaprojektowane z myślą o ochronie półprzewodnikowych elementów mocy. Celem niniejszego artykułu jest przedstawienie podstawowych pojęć, parametrów i funkcji tych bezpieczników.
EN
Poly(p-phenylenediamine) is a potential precursor for designing of new materials for optoelectronic application. Synthesis and characterization of poly(p-phenylenediamine) – TiO2 nanocomposites has been demonstrated. Structural change observed due to the formation of nanocomposites was correlated with concomitant change in conducting behavior of the parent polymer. Polymer nanocomposite was synthesized through an in-situ oxidative polymerization technique with simultaneous dispersion of TiO2 nanoparticles. TiO2 nanoparticles were synthesized via sol-gel process. Structural characterization was accomplished by using conventional spectroscopic and imaging techniques. I-V measurement of the nanocomposites revealed that the nearly nonconducting poly(p-phenylenediamine) after structural modification exhibits conductivity of 10-6 S/cm leading to formation of wide band gap semiconducting materials.
EN
GaN thin films were deposited on p-Si(1 0 0) substrates using RF magnetron sputtering at various RF powers. Influence of RF power on morphological, optical and structural properties of GaN thin films were investigated and presented in detail. XRD results proved that the films were polycrystalline in structure with (1 0 0) and (1 1 0) planes of hexagonal GaN. It was found that increasing RF power led to deterioration of crystal structure of the films due to increased decomposition of GaN. Stress in GaN thin films was calculated from XRD measurements and the reasons for this stress were discussed. Furthermore, it was analyzed and interpreted whether the experimental measurement results support each other. E2 (high) optical phonon mode of hexagonal GaN was obtained from the analysis of Raman results. UV-Vis spectroscopy results showed that optical band gap of the films varied by changing RF power. The reasons of this variation were discussed. AFM study of the surfaces of the GaN thin films showed that some of them were grown in Stranski-Krastanov mode and others were grown in Frank-Van der Merwe mode. AFM measurements revealed almost homogeneous, nanostructured, low-roughness surface of the GaN thin films. SEM analysis evidenced agglomerations in some regions of surface of the films and their possible causes have been discussed. It has been inferred that morphological, optical, structural properties of GaN thin film can be changed by controlling RF power, making them a potential candidate for LED, solar cell, diode applications.
6
Content available remote Current state of photoconductive semiconductor switch engineering
EN
This paper presents the current state of a photoconductive semiconductor switch engineering. A photoconductive semiconductor switch is an electric switch with its principle of operation based on the phenomenon of photoconductivity. The wide application range, in both low and high-power devices or instruments, makes it necessary to take design requirements into account. This paper presents selected problems in the scope of designing photoconductive switches, taking into account, i.e. issues associated with the element trigger speed, uniform distribution of current density, thermal resistance, operational lifespan, and a high, local electric field generated at the location of electrodes. A review of semiconductor materials used to construct devices of this type was also presented.
EN
Herein, we report a successful development of nano-scale pure and Al and Mn co-doped PbI2 using facile microwave-assisted route. Structural study was done through X-ray diffraction analysis of grain size, dislocation density and lattice strain. The crystallite size was found to vary from 28 nm to 40 nm due to Al:Mn co-doping in PbI2. The presence of various vibrational modes was confirmed by FT-IR spectroscopy and red shifting was observed in peak positions compared to the bulk. Surface morphology, examined using a scanning electron microscope, confirmed the formation of single crystal nanosheets of a thickness in the range of 10 nm to 30 nm. The single crystal nanosheets were found to be transformed to large area nanosheets due to the doping. Enhancement in dielectric constant from ~7.5 to 11 was observed with increasing Al doping concentration. Linear attenuation coefficient was calculated and showed the enhancement of blocking gamma rays with increasing doping concentration. Its value was found to increase from 7.5 to 12.8 with the doping. The results suggest that the synthesized nanostructures can be used for detection and absorption of gamma rays emitted by 137Cs and 241Am sources.
PL
W niniejszym artykule przedstawiono serię pomiarów i poszukiwanie metody wykrywania uszkodzeń za pomocą przetwarzania sygnałów emisji akustycznej. Sygnał z czujnika obserwowano i przetwarzano za pomocą oscyloskopu i poddano obróbce cyfrowej. Celem była obserwacja wyjściowego sygnału przy zmianie napięcia zasilania, aby oszacować jego wpływ na sygnał z czujnika.
EN
This paper shows series of measurements and a search for method of signal processing. Sensor signal was obtained with oscilloscope in order to further process it digitally. The change of power supply voltage was also measured to estimated its influence on sensor signal.
PL
W pracy omówiono odkrycia z zakresu występowania nadprzewodnictwa w półprzewodnikach. Materiały te łącząc specyficzne właściwości tych dwóch klas – nadprzewodników i półprzewodników – stwarzają nowe możliwości ich zastosowania, w tym przy konstrukcji przyrządów elektronicznych. Przedstawiono pierwsze, wcześniejsze rezultaty badań półprzewodników nadprzewodzących, w tym przeprowadzone przez autora na selenku lantanu oraz wyniki nowych badań prowadzących do odkrycia nadprzewodników żelazowych, które także oparte są na lantanie i selenie.
EN
In the paper are discussed discoveries from range of occurrence superconductivity in semiconductors. These materials connecting peculiar specificities in these two classes – superconductors and semiconductors bring new capabilities of their applications at construction of electronic instruments. In paper are presented first, earlier results of research of superconducting semiconductors, including carried by author of publication on lanthanum selenide and then results of new research leading to discovery of iron-superconductors, which are also based on lanthanum and selenide.
10
Content available remote Wybrane aspekty projektowania przełączników fotokonduktancyjnych
PL
Półprzewodnikowy przełącznik fotokonduktancyjny to urządzenie, w którym w wyniku pobudzenia sygnałem optycznym, następuje wzrost koncentracji nośników ładunku powodując zmniejszenie oporności materiału półprzewodnikowego nawet o kilka rzędów wielkości. W artykule przedstawiono wybrane aspekty projektowania przełączników fotokonduktancyjnych uwzględniając m.in. kwestie związane z szybkością włączania elementu, równomiernym rozkładem gęstości prądu, wytrzymałością termiczną, czasem eksploatacji i wysokim lokalnym polem elektrycznym wytwarzanym w miejscu elektrod.
EN
A photoconductive semiconductor switch is a device in which density of charge carriers increases causes decreases resistivity of semiconductor as a result of optically triggered. This paper shows selected aspects of photoconductive semiconductor switches designing with regards issue related to the switch rise-times, uniform distributed current density, thermal resistance, device lifetime and high local electric field generated at the electrode site.
PL
HITACHI, dostrzegając aktualne potrzeby rynku, wprowadza tranzystory IGBT nowej generacji w obudowie nHPD2 o niższych stratach mocy, niższej indukcyjności oraz wartościach EMI, torując jednocześnie drogę dla technologii półprzewodników WBG.
PL
W artykule omówiono model matematyczny zjawisk fizycznych opisujących działanie elementu termoelektrycznego jakim jest ogniwo Peltiera. W uproszczeniu omawiany element funkcjonuje jako mała „pompa powietrza” zimnego lub ciepłego. Proces wymiany temperatury między poszczególnymi elementami ogniwa realizowany jest w sposób ciągły tzn. powierzchnia jednego półprzewodnika umieszczonego w module jest chłodzona, druga zaś ogrzewana. Cykl ten realizowany jest jednocześnie na obu elementach półprzewodnikowych. Biorąc pod uwagę, że materiał z którego wykonano element półprzewodnikowy zależny jest od temperatury środowiska w jakim pracuje, stąd w procesie modelowania fizycznego zwrócono szczególną uwagę na poszczególne etapy zmiany temperatury ze stanu zimnego w gorący. Podstawowe zjawiska fizyczne zachodzące w module Peltiera są ściśle powiązane z temperaturą, tak więc parametry użytkowe elementu zależne są od warunków pracy. Proces ten odwzorowano w modelowaniu komputerowym w specjalnie stworzonym do tego celu oprogramowaniu inżynieryjnym, w którym to zweryfikowano zależności matematyczne określające wydajność ogniwa Peltiera. Wyniki zaprezentowane w niniejszym artykule zostały wyznaczone dla pracy ogniwa w temperaturze powietrza mieszczącego się w przedziale (-20°C – +35°C).
EN
The article discusses the mathematical model of physical phenomena describing the operation of the thermoelectric element which is Peltier module. Simply discussed element functions as a small cold or warm "air pump". The process of the temperature exchange between different parts of the cell is executed continuously and it means that the surface of a semiconductor placed in the module is cooled and the other side is heated. This cycle is carried out simultaneously on both side of the semiconductor. The material from which the semiconductor element depends on the temperature of the environment where is place, there was highlighted various stages of temperature changes from cold to hot during the physical modeling. Bearing in mind that the basic physical phenomena occurring in the Peltier module are closely connected to the temperature, the operating parameters element depends on operating conditions. This process is mapped in computer modeling in a specially designed for this purpose engineering software where it was verified mathematical relations which determines the performance of Peltier modules. The presented results in this article are set for the module's operation temperature of air located in the range of between -20°C and + 35°C.
EN
This work details about the isolation of CuO nanoflakes by a simple precipitation technique. Further it is coated over ITO substrate using spin coating technique. DSS cell capabilities were checked by placing a drop of plant dye derived from pomegranate. Design/methodology/approach: CuO nano flakes, a novel Nano sized metal oxide have been synthesized by sol-gel method. The synthesised flakes were characterized by using XRD (X-ray diffraction), FESEM, UV-VIS and PL measurements techniques. XRD studies show that, the copper oxide formed has monoclinic structure. Findings: The grain size of the synthesized copper oxide nanoflakes were measured from FESEM and found that the size was around 200 nm. The UV-VIS measurement show that the band gap of CuO nanoflakes were found to be 3.03 eV, which is in the range of a good semiconductor. Finally, the dye sensitized solar cell was fabricated and its power conversion efficiency η (PCE) was determined. Practical implications: The search for green sources or generators of energy is considered as one of the priorities in today's society and occupies many policy maker’s agenda. It is believed that nanocrystalline photovoltaic devices are becoming viable contender for large scale future solar energy converters.
EN
Cadmium sulfide (CdS) nanorods with a diameter of 50 nm and length of approximately 200 nm have been synthesized using combined sonochemical-solvothermal method. Structural properties of CdS nanoparticles synthesized by this method have been compared with the CdS nanoparticles synthesized by sonochemical method alone. The synthesized CdS nanostructures have been characterized using X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) methods. In addition, the factors affecting the formation of the structures, including reaction time, different type and ratio of precursors, such as sulphur source, have been investigated. Comparison of the results obtained by both the synthesis methods revealed CdS nanoparticles synthesized by the combined sonochemical-solvothermal method to be of high morphological homogeneity compared to the sonochemical method alone. It is interesting to note that ethylenediamine has been found to be prevented from agglomeration by using the combined sonochemical-solvothermal method as the synthesis method. A modified growth mechanism under the inducement of ethylenediamine solutions for the CdS nanorods has been suggested.
EN
The present study concerns numerical simulations and experimental measurements on the influence of inlet gas mass flow rate on the growth rate of aluminum nitride crystals in Metalorganic Vapor Phase Epitaxy reactor model AIX-200/4RF-S. The aim of this study was to design the optimal process conditions for obtaining the most homogeneous product. Since there are many agents influencing reactions relating to crystal growth such as temperature, pressure, gas composition and reactor geometry, it is difficult to design an optimal process. Variations of process pressure and hydrogen mass flow rates have been considered. Since it is impossible to experimentally determine the exact distribution of heat and mass transfer inside the reactor during crystal growth, detailed 3D modeling has been used to gain insight into the process conditions. Numerical simulations increase the understanding of the epitaxial process by calculating heat and mass transfer distribution during the growth of aluminum nitride crystals. Including chemical reactions in the numerical model enables the growth rate of the substrate to be calculated. The present approach has been applied to optimize homogeneity of AlN film thickness and its growth rate.
EN
The paper presents the results of investigations of zinc oxide (ZnO) layers as a potential sensing material, being affected by certain selected gaseous environments. The investigations concerned the optical transmission through thin ZnO layers in wide spectral ranges from ultraviolet to the near infrared. The effect of the gaseous environment on the optical properties of zinc oxide layers with a thickness of ~ 400 nm was analyzed applying various technologies of ZnO manufacturing. Three kinds of ZnO layers were exposed to the effect of the gaseous environment, viz.: layers with relatively slight roughness (RMS several nm), layers with a considerable surface roughness (RMS some score of nm) and layers characterized by porous ZnO structures. The investigations concerned spectral changes in the transmission properties of the ZnO layers due to the effect of such gases as: ammonia (NH3), hydrogen (H2), and nitrogen dioxide (NO2) in the atmosphere of synthetic air. The obtained results indicated the possibility of applying porous ZnO layered structures in optical gas sensors.
PL
Otrzymano 2 porfirazyny posiadające peryferyjne ugrupowania 4-nitroimidazolilobutylosulfanylowe. Były to porfirazyna bezmetaliczna oraz porfirazyna posiadająca w centrum koordynacyjnym jon manganu(III). Związki te scharakteryzowano z wykorzystaniem spektrometrii mas oraz spektroskopii UV–Vis. Porfirazynę manganową oceniono pod względem właściwości elektrokatalitycznych w kierunku redukcji tlenu. Stwierdzono, że modyfikacja elektrody z węgla szklistego za pomocą zaadsorbowanej cienkiej warstwy porfirazyny manganowej umożliwia poprawę wydajności reakcji elektroredukcji tlenu.
EN
Porphyrazine with peripheral 4-nitroimidazolylbutylsulfanyl substituents was complexed with Mn(III) ion and studied towards O2 redn. were also detd. The glassy C electrode modified with a thin layer of adsorbed Mn porphyrazine showed an improved efficiency in O2 electroredn.
EN
This paper describes the growth of Cd doped ZnO thin films on a glass substrate via sol-gel spin coating technique. The effect of Cd doping on ZnO thin films was investigated using X-ray diffraction (XRD), UV-Vis spectroscopy, photoluminescence spectroscopy, I-V characteristics and field emission scanning electron microscopy (FESEM). X-ray diffraction patterns showed that the films have preferred orientation along (002) plane with hexagonal wurtzite structure. The average crystallite sizes decreased from 24 nm to 9 nm, upon increasing of Cd doping. The films transmittance was found to be very high (92 to 95 %) in the visible region of solar spectrum. The optical band gap of ZnO and Cd doped ZnO thin films was calculated using the transmittance spectra and was found to be in the range of 3.30 to 2.77 eV. On increasing Cd concentration in ZnO binary system, the absorption edge of the films showed the red shifting. Photoluminescence spectra of the films showed the characteristic band edge emission centred over 377 to 448 nm. Electrical characterization revealed that the films had semiconducting and light sensitive behaviour.
EN
Accurate demand forecasting is critical in the semiconductor industry due to high production costs, long lead times, and high market volatility. To remain competitive, companies strive for accurate forecasts to drive their planning cycles and meet customer demand. Although an organisation may not be able to control the accuracy of forecast received due to externalities, they can define the granularity which is most suited to the purpose of the forecasting. Infineon Technologies uses different product granularities for the sales and marketing forecast, for the operational demand forecast and for the monthly volume rolling forecast (VRFC). The latter is the subject of this work. This paper presents the impact of forecast granularity for the VRFC on the accuracy of the plan and checks the dependency of this forecast accuracy on time over the entire planning horizon. Sources of inaccuracies were also identified through discussion with the company experts. The results of this study indicate that granularities and time do have significant impact over the plan accuracy.
20
Content available remote Jonoluminescencja SiC wzbudzana bombardowaniem jonami H+
PL
Zaprezentowano wyniki badań jonoluminescencji węglika krzemu bombardowanego jonami H+ o energiach 120 i 180 keV. Widma jonoluminescencji w zakresie 400-800 nm mają charakter ciągły z maksimum odpowiadającym fali o długości 730 nm. Badano także zmiany natężenia świecenia wywołane bombardowaniem jonowym. Zaobserwowano bardzo szybkie (dwa rzędy wielkości) osłabienie świecenia (dawki rzędu 4·1014 H+/cm2) wywołane zwiększającą się ilością defektów w tarczy. Artykuł zawiera także prezentację aparatury pomiarowej.
EN
Experimental results of the silicon carbide ionoluminescence induced by 120 and 180 keV H+ ion beams. The obtained spectra in the range 400-800 nm are continuous with the maximum at approximately 730 nm. Changes of the luminescence intensity caused by accumulated irradiation fluence were also studied. A very fast decrease of luminescence intensity (by two orders of magnitude) for a relatively small fluence (4·1014 H+/cm2) due to the increasing damage ot the target was observed. A brief description of experimental set-up is also given.
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