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1
Content available remote Badanie elektrycznych właściwości powierzchni heterostruktur AlGaN/GaN/Si techniką skaningowej mikroskopii pojemnościowej
Szyszka A., Szymański T., Tłaczała M., Wośko M., Paszkiewicz R.
Przegląd Elektrotechniczny
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2017
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R. 93, nr 8
58--60
PL
Znaczne niedopasowanie stałych sieciowych oraz współczynników rozszerzalności cieplnej występujące pomiędzy warstwą epitaksjalną, a podłożem w heterostrukturach AlGaN/GaN/Si skutkuje dużą ilością defektów strukturalnych oraz występowaniem niejednorodności właściwości półprzewodnika. W prezentowanej pracy do zobrazowania lokalnych powierzchniowych niejednorodności elektrycznych właściwości AlGaN/GaN osadzanych na podłożu krzemowym techniką MOCVD została wykorzystana technika skaningowej mikroskopii pojemnościowej. Z analizy dwuwymiarowych map sygnału SCM oraz widm dC/dVAmp =f(VDC) w różnych obszarach powierzchni próbki wynika, że ujemny ładunek zgromadzony na dyslokacjach wstępujących w warstwach epitaksjalnych wpływa na właściwości powierzchni, lecz może nie mieć zdecydowanego wpływu na powstawanie dwuwymiarowego gazu elektronowego na interfejsie AlGaN/GaN.
EN
Large mismatch of lattice constants and thermal expansion coefficients between materials in AlGaN/GaN/Si heterostructures lead to high density of structural defects and material inhomogeneities in layers. In the presented work, local electronic properties of AlGaN/GaN/Si heterostructures are investigated using scanning capacitance microscopy. Analysis of two dimensional images of SCM signal and dC/dVAmp =f(VDC) spectrum allowed to conclude that negative charge accumulated at dislocations in epitaxial layers could affect the surface electronic state of the structure but might not have major impact on two dimensional electron gas formation at the AlGaN/GaN interface.
2
Content available remote Scanning capacitance microscopy characterization of AIIIBV epitaxial layers
Szyszka A., Obłąk M., Szymański T., Wośko M., Dawidowski W., Paszkiewicz R.
Materials Science Poland
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2016
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Vol. 34, No. 4
845--850
EN
The applicability of scanning capacitance microscopy (SCM) technique for chosen electrical properties characterization of AIIIBV structures fabricated by Metalorganic Vapor Phase Epitaxy (MOVPE) was examined. The calibration curves for quantitative characterization of doping levels in GaAs layers were created. The AlGaN/GaN/Si heterostructures for high electron mobility transistor fabrication and InGaAs tunnel junction for tandem solar cell characterization were presented. The crucial factors of measurement conditions which could influence the obtained results were also discussed.
3
Content available remote Evaluation of AlGaN/GaN heterostructures properties by QMSA and AFM techniques
Szyszka A., Wośko M., Paszkiewicz B., Tłaczała M.
Materials Science Poland
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2013
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Vol. 31, No. 4
543--547
EN
Atomic force microscopy and Quantitative Mobility Spectrum Analysis (QMSA) were applied for characterization and evaluation of the quality of AlGaN/GaN heterostructures. The structural uniformity, growth mode and electrical properties of the heterostructures were determined. The obtained results indicated that the time of growth of the low temperature GaN nucleation layer influenced the morphology and electrical properties of the AlGaN/GaN heterostructure.
4
Content available Ecological and technical requirements of radioactive waste utilisation
Borowski G., Wośko M.
Journal of Ecological Engineering
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2013
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Vol. 14, nr 1
40--47
EN
The paper presents a survey of radioactive waste disposal technologies used worldwide in terms of their influence upon natural environment. Typical sources of radioactive waste from medicine and industry were presented. In addition, various types of radioactive waste, both liquid and solid, were described. Requirements and conditions of the waste’s storage were characterised. Selected liquid and solid waste processing technologies were shown. It was stipulated that contemporary methods of radioactive waste utilisation enable their successful neutralisation. The implementation of these methods ought to be mandated by ecological factors first and only then economical ones.
5
Wykorzystanie zaawansowanych trybów mikroskopii sił atomowych w badaniach struktur i przyrządów półprzewodnikowych
Szyszka A., Macherzyński W., Prażmowska J., Wośko M., Stafiniak A., Gryglewicz J., Ramiączek-Krasowska M., Paszkiewicz B., Jankowski B., Ściana B., Paszkiewicz R., Tłaczała M.
Elektronika : konstrukcje, technologie, zastosowania
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2012
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Vol. 53, nr 2
55-58
PL
W pracy przedstawione zostały wyniki charakteryzacji lokalnych właściwości detektorów MSM (Metal-Semiconductor-Metal) oraz rezystancyjnych wytworzonych w warstwach GaN, struktur tranzystorów unipolarnych wykonanych w warstwach azotku galu, cienkich warstw metali katalitycznych, heterostruktur AlAs/AIGaAs/GaAs oraz powierzchni węglika krzemu wykonanych różnymi trybami mikroskopii sił atomowych. Badania zostały przeprowadzone metodami Skaningowej Mikroskopii Potencjału Powierzchniowego SSPM (ang. Scanning Surface Potential Microscopy), Skaningowej Mikroskopii Rezystancji Rozproszonej SSRM (ang. Scanning Spreading Resistance Microscopy) oraz obrazowania fazowego.
EN
In this work characterization results of MSM (metal-semiconductor-metal) and resistive detectors fabricated in gallium nitride layers, GaN based unipolar transistors, thin catalytic metal layers, AlAs/AIGaAs/GaAs heterostructures and silicon carbide surface by various techniques of atomic force microscopy are presented. The examinations were performed by Scanning Surface Potential Microscopy (SSPM), Scanning Spreading Resistance Microscopy (SSRM) and in phase imaging mode.
6
Czujnik wodoru AlGaN/GaN FAT-HEMT
Paszkiewicz B., Wośko M., Macherzyński W., Paszkiewicz R., Tłaczała M.
Elektronika : konstrukcje, technologie, zastosowania
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2012
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Vol. 53, nr 2
58-60
PL
Azotki są doskonałymi materiałami do wytwarzania szeregu elementów. W WEMIF PWr prowadzono badania nad zastosowaniem heterostruktur AlGaN do wytwarzania tranzystorów mikrofalowych, biosensorów i czujników gazów. W artykule przedstawiono charakterystyki tranzystorowych czujników wodoru typu AlGaN/GaN FAT-HEMT {FAT-High Electron Mobility Transistors) z bramką katalityczną Pt. Pokazano, że tego typu czujniki mogą być stosowane do detekcji wodoru w szerokim zakresie koncentracji od 0,1 ppm do 10000 ppm.
EN
Nitrides are attractive materials for numerous devices applications. The researches were carried out at WEMiF WrUT devoted to application of AlGaN/GaN heterostructures for fabrication of microwave HEMT transistors, biosensors and gas sensors. The article presents the hydrogen sensing characteristics of FAT-type AlGaN/GaN HEMT with catalytic Pd electrode. It was shown that FAT type Pt/AIGaN/GaN HEMTs have the ability to detect hydrogen in wide range of hydrogen concentration from 0.1 ppm to 10000 ppm.
7
Content available remote Reverse engineering of AlxGa₁₋xAs/GaAs structures composition by reflectance spectroscopy
Wośko M., Paszkiewicz B., Tarnowski K., Ściana B., Radziewicz D., Salejda W., Paszkiewicz R., Tłaczała M.
Opto-Electronics Review
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2011
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Vol. 19, No. 4
418-424
EN
The paper presents the application of non-modulation reflectance method for composition profiling of epitaxial AlxGa₁₋xAs/GaAs structures. This non-destructive method is based on spectral measurements and theoretical reflectance spectrum matching. This is a very accurate and sensitive method of determining the Al composition in AlxGa₁₋xAs layers and structures with resolution down to 1 nm. In this work, the authors describe theoretic principles of this method and present experimental results of characterization of different AlGaAs structures to prove the potential of the worked out method.
8
Reaktywne trawienie jonowe heterostruktur AlGaN/GaN w plazmie Cl₂/BCl₃
Gryglewicz J., Oleszkiewicz W., Wośko M., Szyszka A., Paszkiewicz B.
Elektronika : konstrukcje, technologie, zastosowania
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2011
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Vol. 52, nr 11
19-21
PL
W procesie reaktywnego trawienia jonowego (RIE) wielkiej częstotliwości (w.cz) heterostruktur AlGaN/GaN, badano wpływ oddziaływania potencjału auto-polaryzacji dc podłoży (dc bias) oraz mocy wyładowania w.cz. na morfologię trawionej powierzchni oraz szybkość trawienia azotku galowo-glinowego. Procesy trawienia heterostruktur AlGaN/GaN, wytworzonych przy ciśnieniu atmosferycznym, techniką LP-MOVPE, wykonywano w urządzeniu Oxford Instruments Plasmalab 80Plus RIE. Szybkości trawienia oraz wpływ oddziaływania bombardowania jonowego na trawioną powierzchnię podloża badano przy użyciu mikroskopu sił atomowych (AFM) firmy Veeco Instruments pracującym w modzie tappingu. Podłoża testowe trawiono w plazmie chlorowej w stałej proporcji mieszaniny gazów CI₂/BCI₃/Ar.
EN
This work is concentrated on description of influence of process conditions on RIE of AlGaN/GaN heterostructures results, especially the influence of self-dc bias and rf power on morphology and etch rate of AlGaN. In study Oxford Instruments Plasmalab80 RIE tool was used to perform RIE processes on heterostructures grown using MOVPE technique at atmospheric pressure. The etch rates and the influence of ion bombardment on the heterostructures surface was studied by atomic force microscope (AFM) in tapping mode. The test heterostructures were etched in chlorine-based plasma at constant gas mixture of CI₂ /BCI₃/Ar.
9
Content available remote New method of MOVPE process design for the growth of FGM AlGaAs/GaAs photodetectors
Wośko M., Paszkiewicz B., Radziewicz D., Ściana B., Paszkiewicz R., Tłaczała M., Kovac J., Vincze A.
Optica Applicata
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2009
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Vol. 39, nr 4
739-747
EN
In this paper, the authors present a new attempt to the growth of AlGaAs structures with continuous change of aluminum content by metalorganic vapor phase epitaxy (MOVPE) technique. The new method of design of multistage growth process for functionally graded semiconductor materials (FGM) has been proposed. A comparison between classical single stage and multistage growth process has been carried out. The analysis of PVS, ECV and SIMS results of fabricated photodetector structures shows significant differences in composition profile of theoretically estimated and fabricated structures, and prove that the new conception of multistage process has more advantages over classical single stage procedure.
10
Content available remote A(III)B(V) detectors with graded active region
Wośko M., Paszkiewicz B., Szyszka A., Macherzyński W., Radziewicz D., Ściana B., Paszkiewicz R., Tłaczała M., Sęk G., Poloczek P., Motyka M., Misiewicz J.
Materials Science Poland
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2008
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Vol. 26, No. 1
87--94
EN
Results of modelling and fabrication of photodetectors with composition graded active layers have been presented. Simulated and measured spectral characteristics of the proposed detectors have been shown. Advantages of such structures have been discussed with respect to conventional detectors with non-graded active areas as well as some technological problems of compositionally graded semiconductor layers.
11
Content available remote AIII-BV(N) photodetectors with functionally graded active area
Wośko M., Paszkiewicz B., Piasecki T., Prażmowska J., Paszkiewicz R., Tłaczała M.
Optica Applicata
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2007
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Vol. 37, nr 1-2
161-165
EN
Functionally graded materials (FGM) find widespread for mechanical applications. Nowadays, they become more and more attractive in fabrication of electronic and optoelectronic devices. This is due to by their unique properties. FGM are potential candidates for high sensitive photonic devices which could operate in a wide spectral range (also for voltage tunable photodetectors). In this paper, the analysis of several photodetector constructions fabricated in FGM has been presented. The influence of AIII-BV(N) grading layers composition and configuration of the detector on its optical and electrical properties has been discussed. Also, a comparison between conventional non-graded and graded devices has been made. All simulations presented in the work are performed by the specialized software designed for modeling AIII-BV(N) graded structures. The software allow us to calculate both the parameters of FGM structure and device characteristics. During the simulation process it was noticed that the bandgap gradation in phototodetector active area improved its sensitivity up to 150% compared to classical, non-graded structures. Also, another effect such the wavelength sensitivity observed in these devices makes them very attractive for applications in which the high sensitive wavelength dependence is a key factor.
12
Content available remote Influence of materials grain structure on the performance of optoelectronic devices
Szyszka A., Paszkiewicz B., Wośko M., Tłaczała M.
Optica Applicata
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2005
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Vol. 35, nr 3
549-554
EN
The influence of grain structure of materials on optoelectronic devices performance was examined by light beam induced current (LBIC) technique. AIGaN metal-semiconductor-metal (MSM) detectors and polycrystalline silicon solar cells were examined. In case of AIGaN MSM structures, the effective region of carrier collection of contact electrodes was estimated as hundreds of nanometers. For these structures, the regions, where measured signals were two orders of magnitude larger than the average signal, were also observed. Measurements of polycrystalline solar cells allow us to determine the recombination activity of grain boundaries. LBIC method was applied to investigate layers quality used for MSM detectors and solar cells fabrication.
13
Content available remote Applications of functionally graded materials in optoelectronic devices
Wośko M., Paszkiewicz B., Piasecki T., Szyszka A., Paszkiewicz R., Tłaczała M.
Optica Applicata
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2005
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Vol. 35, nr 3
663-667
EN
Up to now research on functionally graded materials (FGM) was focused on their mechanical and strength properties. The paper presents a review of possible applications of AIII-BV group materials with graded composition for optoelectronic devices, such as p-i-n diodes, heterojunction photodetectors and lasers. Nowadays, there are no optoelectronic devices fabricated from FGM. The theoretical simulation showed that devices with FGM active region would have superior characteristics compared with classical constructions.
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