Search results

1

Transport Behaviour in Low-Resistance Metal/p-GaAs Interfaces

100%

Kamińska E., Piotrowska A., Kasjaniuk S., Gierlotka S.

Acta Physica Polonica A

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1996

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vol. 90

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issue 4

843-846

EN

The relationship between electrical properties and microstructure of pure Zn and AuZn contacts to p-GaAs has been studied. The obtained results prove that mechanism responsible for the ohmic behaviour of these contacts is associated with the lowering of the potential barrier at metal/semiconductor interface, resulting from the phase transformations in the metallization.

2

Easy-Plane Magnetic Anisotropy Induced by Stress-Annealing in Finemet-Type Materials

88%

Lachowicz H., Kane S., Gupta A., Gierlotka S., Pałosz B.

Acta Physica Polonica A

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1998

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vol. 93

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issue 5-6

799-804

EN

It is shown that annealing under stress of FINEMET-type metallic glass ribbon (FeCuNbSiB) induces magnetic anisotropy of an easy-plane type (cross-section of the ribbon). This conclusion has been drawn analyzing experimental results obtained by means of Kerr-effect (domain structure) and Mössbauer spectroscopy operating in the so-called "magic angle" configuration which allows us to calculate all three spatial components of magnetization. Additionally, it is also shown that no crystallographic texture is created in the sample after stress-annealing, the feature which would have been an origin of the observed anisotropy.

3

Magnetization of GaMnN Ceramics Prepared from Nanopowders by an Anaerobic Synthesis and High-Pressure High-Temperature Sintering

76%

Gosk J., Drygaś M., Janik J., Gierlotka S., Pałosz B., Twardowski A.

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EN

Herein, we report a study on magnetic properties of GaMnN ceramics prepared by no additive high-pressure high-temperature sintering of a range of nanopowders, the latter made via an anaerobic synthesis method in the Ga/Mn bimetallic system at various nitridation temperatures and different levels of initial Mn concentration. Measurements of the magnetization as a function of temperature and magnetic field for the ceramics and parent nanopowders showed a typical paramagnetic behavior. Antiferromagnetic interactions between Mn-ions incorporated in the GaN lattice, GaMnN, were revealed and shown to be much stronger in the ceramics than in the respective nanopowders. In addition, in all of these materials an antiferromagnetic contribution originating from a residual Mn₂SiO₄ by-product was also observed. The highest calculated Mn concentration in the nanopowders reached 3.4 at.%. Complex mixtures of gallium nitride polytypes with multimodal particle size distributions in the nanosized range (small nano: 2-8 nm, large nano: 35-60 nm) were converted upon sintering to the single hexagonal GaN phase with average crystallite sizes of 40-80 nm and higher. For the optimal 700°C-treated materials, the Mn concentration in the parent GaMnN nanopowder was 3.2 at.% whereas in the derived ceramics it amounted to 5.5 at.%. At the same time, contributions of the adventitious Mn₂SiO₄ by-product significantly decreased upon sintering.

4

Diffraction Studies of Nanocrystals: Theory and Experiment

64%

Palosz B., Grzanka E., Gierlotka S., Stel'makh S., Pielaszek R., Bismayer U., Neuefeind J., Weber H., Palosz W.

Acta Physica Polonica A

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2002

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vol. 102

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issue 1

57-82

EN

Based on theoretical calculations of powder diffraction data it is shown that the assumption of the infinite crystal lattice for small particles is not justified, leads to significant changes of the diffraction patterns, and may lead to erroneous interpretation of the experimental results. An alternate evaluation of diffraction data of nanoparticles, based on the so-called "apparent lattice parameter", alp, is proposed.

5

Interaction of Au with GaSb and its Impact on the Formation of Ohmic Contacts

64%

Piotrowska A., Kamińska E., Piotrowski T., Kasjaniuk S., Guziewicz M., Gierlotka S., Lin X. W., Liliental-Weber Z., Washburn J., Kwiatkowski S.

Acta Physica Polonica A

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1995

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vol. 87

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issue 2

419-422

EN

Interfacial reactions between GaSb and Au were studied by Rutherford backscattering, X-ray diffraction, and cross-sectional transmission electron microscopy. Evaluation of the extent to which the GaSb substrate decomposes was of primary concern. The results give evidence that the reaction takes place even at temperatures as low as 180°C. High reactivity of gold towards GaSb revealed by this study demonstrates that Au-based metallization is not a good candidate for device quality ohmic contacts to GaSb-based devices.

6

Generation and Relaxation of Microstrains in GaN Nanocrystals under Extreme Pressures

64%

Grzanka E., Palosz B., Gierlotka S., Pielaszek R., Bismayer U., Janik J., Wells J., Palosz F., Porsch F.

Acta Physica Polonica A

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2002

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vol. 102

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issue 2

167-174

EN

Nanocrystalline powders of GaN with grain sizes ranging from 2 to 30 nm were examined under high external pressures by in situ diffraction techniques in a diamond anvil cell at DESY (HASYLAB, Station F3). The experiments on densification of pure powders under high pressure were performed without a pressure medium. The mechanism of generation and relaxation of internal strains and their distribution in nanoparticles was deduced from the Bragg reflections recorded in situ under high pressures at room temperature. The microstrain was calculated from the full-width at half-maximum (FWHM) values of the Bragg lines. It was found that microstrains in GaN crystallites are generated and subsequently relaxed by two mechanisms: generation of stacking faults and change of the size and shape of the grains occurring under external stress.

7

Fabrication and Physical Properties of SiC-GaAs Nano-Composites

64%

Kalisz G., Grzanka E., Wasik D., Świderska-Środa A., Gierlotka S., Borysiuk J., Kamińska M., Twardowski A., Pałosz B.

Acta Physica Polonica A

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2005

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vol. 108

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issue 4

717-721

EN

Nano-composites consisting of primary phase of hard nanocrystalline SiC matrix and the secondary nanocrystalline semiconductor (GaAs) phase were obtained by high-pressure zone infiltration. The synthesis process occurs in three stages: (i) at room temperature the nanopowder of SiC is compacted along with GaAs under high pressure up to 8 GPa, (ii) the temperature is increased above the melting point of GaAs up to 1600~K and, the pores are being filled with liquid, (iii) upon cooling GaAs nanocrystallites grow in the pores. Synthesis of nano-composites was performed using a toroid-type high-pressure apparatus (IHPP of the Polish Academy of Sciences, Warsaw) and six-anvil cubic press (MAX-80 at HASYLAB, Hamburg). X-ray diffraction studies were performed using a laboratory D5000 Siemens diffractometer. Phase composition, grain size, and macrostrains present in the synthesized materials were examined. Microstructure of the composites was characterized using scanning electron microscopy and high resolution transmission electron microscopy. Far-infrared reflectivity measurements were used to determine built-in strain.

8

Electrical and Structural Properties of Ohmic Contacts to n-Type and High Resistivity CdTe

52%

Kamińska E., Piotrowska A., Guziewicz M., Gierlotka S., Papis E., Łusakowski J., Szadkowski K., Kwiatkowski S., Dietl T., Grabecki G., Jaroszyński J., Karczewski G., Zakrzewski A. K.

Acta Physica Polonica A

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1995

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vol. 87

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issue 2

411-414

EN

The interaction between CdTe and In during the formation of an ohmic contact has been investigated. Emphasis is placed on the study of the effect of thermally induced sublimation of cadmium on electrical properties of contacts. Presented results prove the effectiveness of cap annealing and rapid thermal processing in fabrication of improved ohmic contacts with limited Cd losses during the contacting procedure.

Refine search results

Transport Behaviour in Low-Resistance Metal/p-GaAs Interfaces

Easy-Plane Magnetic Anisotropy Induced by Stress-Annealing in Finemet-Type Materials

Magnetization of GaMnN Ceramics Prepared from Nanopowders by an Anaerobic Synthesis and High-Pressure High-Temperature Sintering

Diffraction Studies of Nanocrystals: Theory and Experiment

Interaction of Au with GaSb and its Impact on the Formation of Ohmic Contacts

Generation and Relaxation of Microstrains in GaN Nanocrystals under Extreme Pressures

Fabrication and Physical Properties of SiC-GaAs Nano-Composites

Electrical and Structural Properties of Ohmic Contacts to n-Type and High Resistivity CdTe