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1

Potential Energy Surfaces for H Adsorbed at 4H-SiC{0001} Surfaces

100%

Wachowicz E., Kiejna A.

Acta Physica Polonica A

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2013

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vol. 124

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issue 5

765-767

EN

The constant adsorption energy surfaces for hydrogen adsorbed on Si- and C-terminated hexagonal 4H-SiC{0001} surfaces have been calculated within density functional theory framework. The two unreconstructed and one reconstructed √3 × √3 surfaces were taken into account. We show that on all surfaces there is a global energy minimum indicating the most favourable adsorption site corresponding to H atom adsorption on-top of the topmost substrate layer atom. In case of reconstructed surface, there is another small and shallow local minimum. Moreover, the diffusion barrier is much higher at reconstructed surface than at unreconstructed ones.

2

Dye Aggregation Influence on Dye Sensitized Solar Cell Performance in Nanocoral ZnO-Based Thin Film Cells Sensitized with N-719 and Rose Bengal Dyes

100%

Borysiewicz M., Chusnutdinow S., Wzorek M., Wojciechowski T.

Acta Physica Polonica A

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2016

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vol. 130

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issue 5

1187-1189

EN

Dye sensitized solar cells were fabricated using ZnO nanostructured photoelectrodes sensitized with N-719 or Rose Bengal dyes. We assessed the device performance as a function of the sensitization time and found a dependence on time for the N-719 and no significant changes for the Rose Bengal. Furthermore, we observe that the structure of the N-719 molecule beneficial for sensitization of TiO₂ may lead to the degradation of the ZnO crystals and a growth of an amorphous shell limiting dye performance in the cells.

3

Microscopic Investigation of SiC Epitaxial Layers οn On-Axis 4H-SiC Substrates Using Kelvin Probe Force Microscopy

100%

Kościewicz K., Bożek R., Strupiński W., Olszyna A.

Acta Physica Polonica A

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2009

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vol. 116

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issue S

S-69-S-71

EN

We report on Kelvin probe force microscopy and electron backscatter diffraction measurements of 3C-SiC epitaxial layers grown on exactly oriented Si-face 4H-SiC (0001) substrates in a horizontal hot-wall chemical vapor deposition reactor, in the temperature range from 1150°C to 1620°C, under H_{2} or H_{2} +SiH_{4} atmosphere. The investigated layers were doped with nitrogen (for n-type) and aluminium (for p-type). The electron backscatter diffraction analysis revealed structure of polytype 3C blocks with a relative rotation of 60 and/or 120°. The Kelvin probe force microscopy measurements revealed cubic substructure as a equilateral triangle objects contrast which is characteristic of 3C silicon carbide polytype. The surface potential contrast was found to be dependent on the type and concentration of doping, which could be explained in terms of the impurities accumulation at block boundaries.

4

Superconductivity of Niobium Thin Films in the BiOCl/Nb Heterostructures

100%

Lotnyk D., Komanický V., Bunda V., Feher A.

Acta Physica Polonica A

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2017

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vol. 131

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issue 4

1030-1032

EN

In the current paper, electrical transport properties of 25 nm thick Nb films sputtered on the photosensitive semiconductor BiOCl were investigated in the temperature range 7.5 K ≤ T ≤8.5 K. The influence of green (532 nm) and red (640 nm) laser excitations on resistive superconducting transitions of the niobium thin films on a silicon glass and BiOCl single crystal substrates were studied. The temperature dependences of the resistivity for Nb are in good agreement with the McMillan model which indicates the strong influence of the inverse proximity effect induced by the interface. The increased influence of the BiOCl/Nb interface under laser excitation corresponds to the raising of the ratio of the density of normal to superconductivity carriers in the Tıghtarrow0 limit and this observation is in agreement with the photoconductivity study of BiOCl single crystals.

5

Ab Initio Studies of Al and Ga Adsorption on 4H-SiC{0001} Surfaces

100%

Wachowicz E., Sznajder M., Majewski J.

Acta Physica Polonica A

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2012

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vol. 122

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issue 6

1045-1048

EN

Changes in the atomic and electronic structure of Si- and C-terminated 4H-SiC{0001} surfaces resulting from aluminium and gallium adsorption have been studied within density functional theory framework. Al and Ga coverages ranging from a submonolayer to one monolayer were considered. Our results show that Al binds more strongly to both surfaces than Ga. The binding is stronger to the C-terminated surface for both metals. The sites occupied by Al and Ga atoms at 1 monolayer are different and it is due to a different charge transfer from metal to the substrate.

6

Impact of Thin LT-GaN Cap Layers on the Structural and Compositional Quality of MOVPE Grown InGaN Quantum Wells Investigated by TEM

100%

Ivaldi F., Kret S., Szczepańska A., Czernecki R., Kryśko M., Grzanka S., Leszczyński M.

Acta Physica Polonica A

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2011

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vol. 119

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issue 5

660-662

EN

Two samples containing InGaN quantum wells have been grown by metal-organic vapor phase epitaxy on high pressure grown monocrystalline GaN (0001). Different growth temperatures have been used to grow the wells and the barriers. In one of the samples, a low temperature GaN layer (730°C) has been grown on every quantum well before rising the temperature to standard values (900°C). The samples have been investigated by transmission electron microscopy and X-ray diffraction. Photoluminescence spectra have been measured as well. The influence of the LT-GaN has been investigated in regard to its influence on the structural and compositional quality of the sample.

7

EMR Spectra Thin Films Doped with High Concentration of Co and Cr on Quartz and Sapphire Substrates

100%

Cieniek B., Stefaniuk I., Virt I.

Acta Physica Polonica A

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2017

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vol. 132

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issue 1

30-34

EN

We have studied magnetic properties of zinc-oxide composite doped with high concentration (up to 20%) of Co and Cr ions. The pulsed laser deposition method was used to obtain samples on quartz glass and sapphire substrates. Samples were annealed at 100-250°C for ZnO on quartz substrate, and 300-700°C on sapphire substrate. EMR measurements were carried out and temperature dependence of the EMR spectra was obtained. The angular dependence in two samples orientation, vertical and horizontal, were also obtained. Analysis of the temperature dependences of the integral intensity of EMR spectra was carried out using the Curie-Weiss law.

8

Tuning Transparent Supercapacitor Performance by Controlling the Morphology of its ZnO Electrodes

100%

Borysiewicz M., Wzorek M., Ekielski M., Kaczmarski J., Wojciechowski T.

Acta Physica Polonica A

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2017

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vol. 131

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issue 6

1550-1553

EN

Transparent supercapacitors were fabricated using nanostructures ZnO electrodes deposited using reactive magnetron sputtering. By fine tuning the deposition process parameters the electrodes with different morphologies were obtained, from hierarchical through sponge-like to nanocolumnar. The device performance related to the electrode morphology was assessed. It was found that the nanocolumnar electrodes provided best performance both in terms of effective device capacitance (18.3 μF/cm²) and transparency ( ≈ 100% in the visible range). The worst performance, with 80% lower effective capacitance, was obtained in the devices with the sponge-like morphology.

9

Parallel Optical Profilometry Assisted Conception of an Opto-Electronic Illuminator Using a VCSEL and Diffractive Optics

88%

Montgomery P., Serio B., Twardowski P.

Acta Physica Polonica A

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2014

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vol. 125

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issue 4

957-961

EN

Micro-opto electromechanical systems are of growing importance in the development of new miniaturised projection, imaging and detection technologies. Because of the increasing complexity of construction involving layers of microelectronics, optoelectronics and micro-optics, different types of defects can appear that need to be understood and controlled in order for the miniaturised system to operate correctly within the given specifications. We have recently developed a miniaturised structured light (micro-opto electromechanical systems) projector consisting of a multilayer sandwich made of a first layer of 3 bars of 12 VCSEL laser sources, a second layer of Fresnel collimating lenses (diffractive optical elements) and a third layer of Fourier diffractive optical elements to produce the structured light pattern. The main defects that had to be controlled were alignment errors, the first ones being between the emitting surface and the collimating lenses and the second one concerning the lateral alignment of the photomasks used to produce the 4 levels of the Fourier elements. We demonstrate how 3D geometrical shape characterization of the emitting structures and diffractive optical elements surface structures using coherence scanning interferometry played a major role in the conception and fabrication of a prototype micro-optoelectromechanical projection system to understand the source of the alignment errors and to minimise them.

10

X-Ray Photoelectron Spectroscopy - Methodology and Application

88%

Papis-Polakowska E., White R., Deeks C., Mannsberger M., Krajewska A., Strupinski W., Płocinski T., Jankowska O.

Acta Physica Polonica A

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2014

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vol. 125

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issue 4

1061-1064

EN

The crucial measurements aspects of X-ray photoelectron spectroscopy, such as chemical state analysis, depth profiling, mapping, and thickness calculation have been presented. The metal alloys, Ti_2O_5, graphene and type-II InAs/GaSb superlattice structures have been examined by using the new Thermo Scientific K-Alpha X-ray Photoelectron Spectrometer.

Refine search results

Potential Energy Surfaces for H Adsorbed at 4H-SiC{0001} Surfaces

Dye Aggregation Influence on Dye Sensitized Solar Cell Performance in Nanocoral ZnO-Based Thin Film Cells Sensitized with N-719 and Rose Bengal Dyes

Microscopic Investigation of SiC Epitaxial Layers οn On-Axis 4H-SiC Substrates Using Kelvin Probe Force Microscopy

Superconductivity of Niobium Thin Films in the BiOCl/Nb Heterostructures

Ab Initio Studies of Al and Ga Adsorption on 4H-SiC{0001} Surfaces

Impact of Thin LT-GaN Cap Layers on the Structural and Compositional Quality of MOVPE Grown InGaN Quantum Wells Investigated by TEM

EMR Spectra Thin Films Doped with High Concentration of Co and Cr on Quartz and Sapphire Substrates

Tuning Transparent Supercapacitor Performance by Controlling the Morphology of its ZnO Electrodes

Parallel Optical Profilometry Assisted Conception of an Opto-Electronic Illuminator Using a VCSEL and Diffractive Optics

X-Ray Photoelectron Spectroscopy - Methodology and Application