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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

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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.

2

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.

3

Influence of low-temperature annealing of AlGaN/GaN heterostructures on adhesion of evaporated Pt-based Schottky contacts

Głowacki P., Macherzyński W., Paszkiewicz R., Tłaczała M.

Elektronika : konstrukcje, technologie, zastosowania

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2013

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Vol. 54, nr 9

108-110

EN

The paper describes alternative method to improve adhesion of platinum thin layer to AlGaN/GaN heterostructures. Our approach was to use low temperature annealing before and during deposition process. The main goal was to observe if such treatment can provide better quality of Schottky contacts to AlGaN/GaN heterostructures.

PL

Artykuł opisuje alternatywną metodę poprawy adhezji cienkich warstw platynowych do heterostruktur utworzonych na azotku galu. Zastosowano niskotemperaturowe wygrzewanie przed i w trakcie procesu osadzania. Głównym celem było sprawdzenie, czy takie potraktowanie próbki może zapewnić lepszą jakość kontaktów Schottky’ego do heterostruktur AlGaN/GaN.

4

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

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2012

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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.

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

Characterization of AIIIBV epitaxial layers by scanning spreading resistance microscopy

Szyszka A., Ściana B., Radziewicz D., Macherzyński W., Paszkiewicz B., Tłaczała M.

Optica Applicata

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2011

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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.

8

Low resistance ohmic contacts to n-GaAs for application in GaAs/AlGaAs quantum cascade lasers

Karbownik P., Barańska A., Szerling A., Macherzyński W., Papis E., Kosiel K., Bugajski M., Tłaczała M., Jankieła R.

Optica Applicata

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2009

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Vol. 39, nr 4

655-661

EN

This paper reports on the results of optimization of ohmic contacts for GaAs/AlGaAs quantum cascade lasers (QCLs). Technological parameters during optimization concerned surface preparation, evaporation method, and thermal treatment. The aim of this research was to obtain low resistance and time stable ohmic contacts. The average specific contact resistance was 6×10-7 ?cm-2 with record value below 3×10-7 ?cm-2. It appears that the crucial role in contact formation is played by the in-situ surface pretreatment and thermal processing. Circular transmission line method (CTLM) was applied for electrical characterization of Ni/AuGe/Ni/Au metallization system. Secondary ion mass spectroscopy (SIMS) was used for determination of Au diffusion into semiconductor. The system presented was used in fabrication of pulse operating QCLs. The lasers mounted with diamond heat spreaders on copper block cooled by liquid nitrogen (LN) achieved optical powers over 1 W, threshold current density values of 7 kAcm-2 and differential efficiencies above 1 W/A.

9

Effect of annealing temperature on the morphology of ohmic contact Ti/Al/Ni/Au to n-AlGaN/GaN heterostructures

Macherzyński W., Stafiniak A., Szyszka A., Gryglewicz J., Paszkiewicz B., Paszkiewicz R., Tłaczała M.

Optica Applicata

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2009

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Vol. 39, nr 4

673-679

EN

Ohmic contacts to AlGaN/GaN heterostructures which have low contact resistance and good surface morphology are required for the development of high temperature, high power and high frequency electronic devices. One of the keys to the advancement of such devices is the understanding of ohmic contacts formation to epitaxial aluminium gallium nitride layers. The paper presents the investigation of Ti/Al/Ni/Au based ohmic contact to n-AlGaN/GaN heterostructures grown by LP-MOVPE technique. Multilayer metallization of Ti/Al/Ni/Au with thicknesses of 10/100/40/150 nm, respectively, was evaporated by an electron gun (Ti, Ni) and resistance heater (Al, Au). The contacts were annealed at RTA (rapid thermal annealing) system in nitrogen ambient atmosphere over the temperature range from 775 °C to 850 °C. The time of annealing process was 60 seconds. The morphology of Ti/Al/Ni/Au ohmic contacts to n-AlGaN/GaN heterostructures was studied as a function of the annealing process conditions by an optical microscope and AFM (atomic force microscope). Simultaneously, the electrical parameters of Ti/Al/Ni/Au ohmic contacts were studied as a function of the annealing process conditions by the current-voltage (I-V ) method on dedicated test structures. The characteristic resistances of the Ti/Al/Ni/Au/n-AlGaN/GaN ohmic contacts were evaluated from the circular transmission line method (CTLM). The formation and deterioration mechanisms of the ohmic contacts to n-AlGaN/GaN hesterostructures were studied. One of the mechanisms of agglomerates enlargement during the thermal annealing of Ti/Al/Ni/Au metallization has been proposed.

10

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

Urządzenie do szybkiej obróbki termicznej (RTA)

Macherzyński W., Tłaczała M.

Elektronika : konstrukcje, technologie, zastosowania

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2007

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Vol. 48, nr 7

37-38

PL

Formowanie i wtapianie kontaktów metalicznych, szczególnie do półprzewodników z szeroką przerwą wzbronioną, wymaga krótkich czasów procesu oraz wysokich temperatur. Klasyczne wygrzewanie w piecu oporowym nie spełnia wymagań zaawansowanej elektroniki. Dlatego opracowano i wykonano urządzenie RTA do szybkiej obróbki termicznej. Szeroki zakres temperatur pracy urządzenia (200...1000°C) oraz w pełni programowalny profil temperatury powodują, że jest to doskonałe urządzenie badawcze o szerokim spektrum aplikacji. W urządzeniu zastosowano od 1 do 14 halogenowych promienników podczerwieni o mocy 1,6 kW każdy, promienniki z powłoką tlenku aluminium zwiększającą sprawność przekazywania mocy, reaktor od strony wlotu gazu, zakończony jest specjalną głowicą umożliwiającą jednorodne wymieszanie gazów technologicznych. Szybkie chłodzenie próbki zapewnia podstawa grafitowa o małej masie i wymiarach 30 x 6 x 2 mm.

EN

Post-deposition annealing of a multilayer metallization, for a wide band-gap semiconductors in particular, must be performed in short time and high temperature. Annealing in a classical resistance furnace can not fulfill requirements of the advanced microelectronic devices. This is the reason why we design and set up a rapid thermal annealing (RTA) system. Wide temperature range of the RTA system (200...1000°C) and full-programmable temperature profile caused that this system is dedicated for research and can find wide range of application. The system can be equipped with one to fourteen short wavelength halogen-IR-emitters 1.6 kW each, with integrated alumina ceramic reflector. The application of a reflector increases the efficiency of transfer of IR power. Low mass of graphite susceptor of a dimension 30 mm x 6 mm x 2 mm allows the fast cooling of a sample. The reactor have a specialized input head which allows the uniform mixing of technological gases.