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1
Content available remote Wpływ światła na rezystancję powierzchniową heterostruktury AlGaN/GaN
Pokryszka P., Paszkiewicz B.
Przegląd Elektrotechniczny
|
2018
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R. 94, nr 9
29--31
PL
Rezystancja powierzchniowa jest jednym z najczęściej wykorzystywanych parametrów elektrycznych wytworzonych cienkich warstw. Szczególną cechą rezystancji powierzchniowej jest jej skalowalność, którą często wykorzystuje się w ocenie jakościowej przyrządów półprzewodnikowych zaprojektowanych w różnej skali. W pracy przedstawiono wpływ pobudzenia UV na GaN. Na podstawie zaprezentowanej metody zbadano wpływ światła na rezystancję powierzchniową oraz uzyskano charakterystykę widmową heterostruktury AlGaN/GaN. Pomiary wykonano z wykorzystaniem struktury testowej typu Hall bar. Wzrost heterostruktury AlGaN/GaN uzyskano metodą MOCVD. Pomiary przeprowadzono w temperaturze pokojowej natomiast czynnikiem pobudzającym było światło z zakresu 280-640 nm. W pracy zbadano i omówiono zmianę rezystancji powierzchniowej w funkcji długości fali światła pobudzającego, analizowano również obecność głębokich poziomów w heterostruktorze AlGaN/GaN.
EN
Sheet resistance is most commonly used electrical parameters of thin films produced. A special feature of sheet resistance is its scalability, which is often used in the qualitative assessment of semiconductor devices designed at different scales. The paper presents the effect of UV excitation on GaN. Based of presented method, influence of light on sheet resistance was investigated and spectral characteristic of AlGaN/GaN heterostructure were obtained. Based on presented method, influence of light on sheet resistance was examined and spectral characteristic of AlGaN/GaN heterostructure were obtained. Measurements were made using the Hall bar test structure. Grown by obtained MOCVD methods. The Hall bar test structures were fabricated and investigated at room temperature and light in 280-640 nm range. The work examines and discusses the change of sheet resistance as a function light was also analyzed in the presence of deep level AlGaN/GaN heterostructure.
2
Content available Improvement of the electron beam lithography contact pads fabrication process
Indykiewicz K., Paszkiewicz R., Paszkiewicz B.
Optica Applicata
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2016
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Vol. 46, nr 2
249--254
EN
In the paper, the verification of using the electron beam lithography technique as a main lithography tool for device fabrication is presented. The results of conducted experiments allow us to minimize the exposition time of big areas and retain acceptable metallic structures resolution and designed distances for structures in the neighborhood of a few micrometers. Conducted statistical analysis allows us to define the significance of the selected factors influence on the objectives of this study.
3
Content available Effect of surface coating with palladium on hydrogen permeability of Pd33Ni52Si15 amorphous alloy membrane
Prochwicz W., Macherzyński W., Paszkiewicz B., Stępień Z.
Optica Applicata
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2016
|
Vol. 46, nr 2
173--179
EN
In the paper, the effect of the surface coating with palladium on hydrogen permeation of a Pd33Ni52Si15 amorphous alloy membrane was investigated. We have measured the hydrogen flow through the melt-spun amorphous membrane covered with palladium film of 10, 20, and 30 nm in thickness. Membranes have been tested in the temperature rage 294–358 K, and at pressure fixed at 102 kPa. We investigate the role of this film thickness on the activation energy for hydrogen permeability. It seemed that a relatively thin layer of the palladium on the surface of the membrane which contains over 30% of this element, should not considerably influence the permeability of the membrane for hydrogen. The membrane hydrogen permeability is correlated to permeation activation energy: the lower activation energy is, the higher permeability is observed. The activation energy for permeation strongly depends on palladium film thickness. The rapid increase of its value was recorded when the film thickness was growing up. As the result, the increase of the film thickness suppressed hydrogen permeability. Our findings are discussed in terms of a potential barrier between the two different phases.
4
Content available remote Hydrogen permeation properties of Pd-coated Pd33Ni52Si15 amorphous alloy membrane
Prochwicz W., Macherzyński W., Paszkiewicz B., Stępień Z. M.
Materials Science Poland
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2015
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Vol. 33, No. 1
56--58
EN
The vast majority of experimental techniques used for the measurements of hydrogen permeability through metallic membranes whose one or both surfaces are covered with a thin Pd film is based on the assumption that a ratio of film-to-membrane thickness is small enough to cause hydrogen flow to be independent of the Pd film thickness. In an attempt to verify this assumption, we have measured the hydrogen flow through the Pd33Ni52Si15 amorphous membrane covered with Pd film of 10, 20, and 30 nm in thickness. Contrary to our expectations, we have found a dramatic decrease in hydrogen flow with the increase in Pd film thickness. Our findings are discussed in terms of potential barrier between the two different phases.
5
Content available Measurements of AlGaN/GaN heterostructures for sensor applications
Hojko M R, Paszuk D, Paszkiewicz B
Optica Applicata
|
2013
|
Vol. 43, nr 1
35--38
EN
In the paper, the behavior of AlGaN/GaN HEMT-type heterostructures in a water solution of (KOH + HCl) with differing pH was studied. The influence of the electrolyte pH on channel pinch-off voltage was measured using impedance spectroscopy methods. It was observed that the change of the pH of electrolyte has a strong effect on the pinch-off voltage of AlGaN/GaN HEMT-type heterostructures independently of the concentration of other ions. In high-pH environment the so-called memory effect of heterostructures was revealed. Its possible origin was discussed. A general theory to explain all results was proposed.
6
Content available Influence of high Al fraction on reactive ion etching of AlGaN/GaN heterostructures
Gryglewicz J, Stafiniak A, Wosko M, Prazmowska J, Paszkiewicz B
Optica Applicata
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2013
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Vol. 43, nr 1
27--33
EN
In this study, the results of reactive ion etching (RIE) process of diversified Al content AlxGa1–xN/AlN/GaN/sapphire heterostructures were presented. The Al fractions of 22, 25, 31 and 36% were examined. An impact of Al content in the heterostructures on the etch rates and surface morphology was investigated. The influence of used Cl2/BCl3/Ar gas mixture with varying of BCl3 flow on the etch rate of Al0.2Ga0.8N/GaN/sapphire, surface morphology and angle of mesa slope, was discussed.
7
Content available Influence of AlN spacer on the properties of AlGaN/AlN/GaN heterostructures
Wosko M, Paszkiewicz B, Paszkiewicz R, Tlaczala M
Optica Applicata
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2013
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Vol. 43, nr 1
61--66
EN
AlGaN/GaN heterostructures attract attention of many research groups over the last decade because of their superior properties (high mobility and saturation velocity of 2DEG) and strong capability in high frequency/power electronics and sensors applications. One of the factors which reduces the mobility of two-dimensional electron gas (2DEG) is the alloy and interface roughness scattering mechanism occurring at the heterointerface. Mathematical calculations of a wave-function of 2DEG in the channel show that theses two phenomena play an important role, due to the fact that some electrons in 2DEG can migrate into AlGaN barrier and be strongly dissipated. One of the proposed solutions against alloy scattering in the buffer layer is the use of thin AlN spacer at the heterointerface between AlGaN and GaN layers. AlN layer enhances the conduction band offset due to a polarization-induced dipole in the AlN layer, and therefore increases carrier confinement. Several Al0.18GaN0.82/AlN/GaN heterostructures with different AlN spacer layer thickness were grown by MOVPE method for studies of the Hall mobility and sheet carrier concentration of 2DEG. Hall measurements performed using Van der Pauw shown mobility maximum at nominally 1.3 nm AlN spacer thickness and almost linear dependence of sheet carrier concentration with AlN spacer thickness in the range from 0.7 to 2 nm.
8
Content available Chemical analysis of Ti/Al/Ni/Au ohmic contacts to AlGaN/GaN heterostructures
Macherzynski W, Indykiewicz K, Paszkiewicz B
Optica Applicata
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2013
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Vol. 43, nr 1
67--72
EN
Ohmic contacts to AlGaN/GaN heterostructures, which have low contact resistance and a good surface morphology, are required for the development of high temperature, high power and high frequency electronic devices. The paper presents the investigation of a Ti/Al based Ti/Al/Ni/Au ohmic contact to AlGaN/GaN heterostructures. Multilayer metallization of Ti/Al/Ni/Au was evaporated by an electron gun (titanium and nickel layers) and a resistance heater (aluminum and gold layers). The contacts were annealed by rapid thermal annealing (RTA) system in a nitrogen ambient atmosphere over the temperature range from 715 to 865 °C. The time of the annealing process was 60 seconds. The chemical analysis, formation and deterioration mechanisms of Ti/Al/Ni/Au ohmic contacts to AlGaN/GaN heterostructures were studied as a function of the annealing process conditions by a scanning electron microscope (SEM) equipped with an energy dispersive spectrometer (EDS).
9
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.
10
Content available remote Analysis of MIS equivalent electrical circuit of Au/Pd/Ti-SiO2-GaAs structure based on DLTS measurements
Kochowski S., Drewniak Ł., Nitsch K., Paszkiewicz R., Paszkiewicz B.
Materials Science Poland
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2013
|
Vol. 31, No. 3
446--453
EN
In this paper MIS equivalent electrical circuit of Au/Pd/Ti–SiO2–GaAs has been analyzed by a comparison of the results obtained from admittance and DLTS spectroscopy. Two groups of peaks with different magnitude and different gate voltage dependence have been observed in DLTS and admittance spectra. Based on the analysis of the peaks behavior, it has been concluded that they are associated with the response of bulk traps and interface states, respectively. In order to characterize bulk traps and interface states responsible for the occurrence of two groups of peaks in normalized conductance spectra we have used the equivalent circuit with two CPE-R branches. The time constant values estimated for both peaks from admittance analysis have been compared with the time constant determined from DLTS analysis. Some discrepancies have been noted between the time constants obtained for interface states whereas the time constants for bulk traps were compatible. It has been also demonstrated that when conductance peaks overlap, the admittance experimental data can be fitted by the equivalent electrical model with only one CPE-R branch. However, in this case incomplete information about the analyzed process has been obtained despite the fact that all model validity criteria can be fulfilled and the model seems to be correct.
11
Content available remote Influence of thermal treatment on the formation of ohmic contacts based on Ti/Al/Ni/Au metallization to n-type AlGaN/GaN heterostructures
Macherzyński W., Paszkiewicz B., Vincze A.
Materials Science Poland
|
2012
|
Vol. 30, No. 4
342--347
EN
Interfacial reactions between Ti/Al/Ni/Au metallization and GaN(cap)/AlGaN/GaN heterostructures at various annealing temperatures ranging from 715 to 865 °C were studied. Electrical current-voltage (I-V) characteristics, van der Pauw Hall mobility measurements and surface topography measurement with atomic force microscopy (AFM) were performed. The ohmic metallizations were annealed at various temperatures in a rapid thermal annealing system and the annealing time of 60 seconds was kept for all samples. To study the in?uence of the parameters of annealing process on the properties of the 2 dimensional electron gas (2DEG) the van der Pauw Hall mobility measurement was used. Interfacial reactions between the contact metals and heterostructures were analyzed through depth pro?les of secondary ion mass spectroscopy. It was observed that transition from nonlinear to linear I-V behavior occurred after the annealing at 805 °C. For the studied samples, the most promising results were obtained for the annealing temperature of 805 °C. This temperatue ensured not only low contact resistance but also made possible to preserve the 2DEG.
12
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
|
2012
|
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.
13
Czujnik wodoru AlGaN/GaN FAT-HEMT
Paszkiewicz B., Wośko M., Macherzyński W., Paszkiewicz R., Tłaczała M.
Elektronika : konstrukcje, technologie, zastosowania
|
2012
|
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.
14
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
|
2011
|
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.
15
Content available remote Characterization of AIIIBV epitaxial layers by scanning spreading resistance microscopy
Szyszka A., Ściana B., Radziewicz D., Macherzyński W., Paszkiewicz B., Tłaczała M.
Optica Applicata
|
2011
|
Vol. 41, nr 2
281--288
EN
One of the electrical characterization techniques of semiconductor structures with nanometer spatial resolution is scanning spreading resistance microscopy (SSRM). The applicability of SSRM technique for characterization of GaAs structures with n-type doping fabricated by metalorganic vapour phase epitaxy (MOVPE) was examined. The influence of scaling effect on the nanometer size AFM tip-semiconductor electrical characteristics was described. The results of characterization of device structure of magnetic field sensitive field effect transistor were presented.
16
Content available remote Application of AFM technique for creation of patterns in nanoscale
Ramiączek-Krasowska M., Szyszka A., Stafiniak A., Paszkiewicz R., Paszkiewicz B., Tłaczała M.
Optica Applicata
|
2011
|
Vol. 41, nr 2
307--314
EN
The lithography is a main technology process which determines the properties of semiconductor devices. The resolution of optical lithography is insufficient for creation of submicrometer patterns, like, e.g., gate electrode in HEMT transistors. Thus, a novel technique that uses AFM technique and common photolithography was proposed. In the paper, the results of nanoscratching lithography were presented and discussed. Also the transmission and root mean square of thin metal films measurements were summarized.
17
Content available remote Reactive ion etching of GaN and AlGaN/GaN assisted by Cl2/BCl3
Gryglewicz J., Oleszkiewicz W., Ramiączek-Krasowska M., Szyszka A., Prażmowska J., Paszkiewicz B., Paszkiewicz R., Tłaczała M.
Materials Science Poland
|
2011
|
Vol. 29, No. 4
260--265
EN
This work reports on the latest results of etching of different AlxGa1??xN/GaN heterostructures in relation to percentage composition of aluminum. The etching processes were carried out in a reactive ion etching (RIE) system using the mixture of BCl3/Cl2/Ar. The topography of the heterostructures surfaces and the slope were controlled using atomic force microsopy (AFM) technique. The photoluminescence spectra were used to determine the surface damage and to calculate the Al content in AlGaN/GaN heterostructures commonly used for high electron mobility transistors (HEMTs) fabrication.
18
Reaktywne trawienie jonowe heterostruktur AlGaN/GaN w plazmie Cl₂/BCl₃
Gryglewicz J., Oleszkiewicz W., Wośko M., Szyszka A., Paszkiewicz B.
Elektronika : konstrukcje, technologie, zastosowania
|
2011
|
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.
19
Content available remote Surface photocurrent nonuniformities in MSM detectors fabricated in gallium nitride heteroepitaxial layers
Szyszka A., Paszkiewicz B., Paszkiewicz R., Tłaczała M.
Optica Applicata
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2009
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Vol. 39, nr 4
723-728
EN
A correlation of surface potential maps and photocurrent distribution images in metal-semiconductor-metal (MSM) structures allows to notice spatial nonuniformities in detector principle of operation. This effect exists only for low frequency modulation of optical excitation. This phenomenon was explained by the inhomogeneity of potential barriers and surface states density in heteroepitaxial gallium nitride layers caused by their columnar structure.
20
Content available remote Properties of AlNx thin films prepared by DC reactive magnetron sputtering
Stafiniak A., Muszyńska D., Szyszka A., Paszkiewicz B., Ptasiński K., Patela S., Paszkiewicz R., Tłaczała M.
Optica Applicata
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2009
|
Vol. 39, nr 4
717-722
EN
In this paper, the results of investigation of the influence of cathode current on optical and dielectric AlNx thin-film properties are presented. AlNx films were prepared by pulsed DC reactive magnetron sputtering of Al target on substrates at room temperature. For characterization of fabricated test structures C-V spectroscopy, ellipsometry measurement and atomic force microscopy (AFM) were used.
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