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1
Content available remote

In Situ Monitoring of Electroepitaxial Growth of Thick AlGaAs Layers

100%
Żytkiewicz Z.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 4
777-780
EN
In situ growth monitoring technique has been used to analyse growth disturbances during the liquid phase electroepitaxial growth of thick AlGaAs layers. It allowed us to explain the nature of growth instability occurring at the end of the growth and affecting the maximum thickness of AlGaAs layers obtainable by liquid phase electroepitaxy.
2
Content available remote

A Role of Intermediate Charge State in the DX Center Photoionisation in Al_{x}Ga_{1-x}As:Se

64%
Kaczor P., Żytkiewicz Z.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 5
801-804
EN
Detailed studies of the DX center absorption are presented. They. studies performed on thick AlGaAs:Te layers, give a strong indication for the influence of the intermediate charge state on the DX center photoionisation.
3
Content available remote

On the High Compositional Uniformity of Thick GaAlAs Layers Grown by Liquid Phase Electroepitaxy

64%
Żytkiewicz Z., Miotkowska S.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
765-768
EN
The results of electroepitaxial growth of thick GaAlAs layers on GaAs substrates are presented. It is experimentally proven that effective convective mixing of the solution volume results in the compositional uniformity of GaAlAs layers, even in spite of the high compositional non-uniformity of the material supplying the solutes (Al, As) to the solution during the growth of the layers. For the first time this allowed us to grow uniform GaAlAs layers with thicknesses up to 200-300 μm in a wide composition range from a small (5 g) amount of solution.
4
Content available remote

New DX-Related Photoinduced Absorption in AlGaAs:Te

64%
Kaczor P., Żytkiewicz Z.
Acta Physica Polonica A
|
1991
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vol. 80
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issue 3
397-400
EN
Absorption measurements on thick AlGaAs:Te layers reveal a new absorption band at ca. 0.55 eV. Also the absorption coefficient of the DX-center ground state was measured directly for the first time.
5
Content available remote

Photoinduced Defects Creation on Sulfur Passivated Surface of GaAs

51%
Żytkiewicz Z., Dobaczewski L., Gomez D., Briones F.
Acta Physica Polonica A
|
1997
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vol. 92
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issue 5
1083-1086
EN
We report on photoinduced defect creation on the sulfurized (100) GaAs surface. The process manifests itself by unrecoverable temporal decrease in the photoluminescence intensity of the GaAs surface treated by (NH_{4})_{2}S_{x} solution. The results are discussed in terms of a photoinduced process of the As_{Ga} antisite generation on the sulfurized surface of GaAs.
6
Content available remote

Electron Spin Resonance Studies of Te Doped AlGaAs Epilayers

51%
Surma M., Godlewski M., Żytkiewicz Z.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 5
817-820
EN
Results of electron spin resonance studies of tellurium doped AlGaAs epilayers are presented. We demonstrate a new approach to the studies of shallow donor-deep DX level transformation upon illumination or with an increase in temperature. The processes can be monitored by observing the changes of magnitude of an unidentified ESR signal of AlGaAs.
7
Content available remote

Molecular Beam Epitaxy of Al_{x}Ga_{1-x}Sb and Al_{x}Ga_{1-x}As: New Donor Doping Sources

51%
Dobaczewski L., Missous M., Singer K., Żytkiewicz Z.
Acta Physica Polonica A
|
1993
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vol. 84
|
issue 4
826-828
EN
The first results obtained with the use of Ga_{2}S_{3} and Ga_{2}Se_{3} compounds as sources of donor elements for molecular beam epitaxy of Al_{x}Ga_{1-x}Sb (0 ≤ x ≤ 1) and Al_{x}Ga_{1-x}As (0 ≤ x ≤ 0.4) are reported. In GaAs free electron concentrations obtained when incorporating the donors from these sources can be easily controlled in the range of three orders of magnitude. For Al_{x}Ga_{1-x}Sb it was possible to compensate the high concentration of native acceptors and to obtain n-type of conductivity.
8
Content available remote

Photo-ESR Study of the DX to Shallow Donor Conversion in Te Doped Al_{x}Ga_{1-x}As

45%
Surma M., Żytkiewicz Z., Fronc K., Stalinga P., Godlewski M.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 4
757-760
EN
Results of detailed electron spin resonance (ESR) study of Te doped Al_{x}Ga_{1-x}As epilayers with x = 0.41, 0.42, and 0.5 Al fractions are presented. It is shown that the ESR signal observed critically depends on cooling steps and that the shallow donor ESR signal can be observed prior to illumination. The first ESR study of AlGaAs layers with removed GaAs substrate are presented. The mechanism of the enhanced photosensitivity of the ESR signal is explained. It is found very paradoxical that the ESR signals decreases upon the illumination even though shallow donor concentration is increased.
9
Content available remote

Alloy Splitting of the Te-DX States in Al_{x}Ga_{1-x}As

45%
Ostermayer G., Jantsch W., Dobosz D., Żytkiewicz Z., Wilamowski Z.
Acta Physica Polonica A
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1993
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vol. 84
|
issue 4
769-772
EN
We report investigations of the Hall effect and conductivity of Te doped Al_{x}Ga_{1-x}As (x = 0.3). After illumination at low temperature, the conductivity decreases in two steps on warming. These steps are explained in terms of the two sets of energy levels associated with two types of Te-DX centers depending on the neighboring host cation (Ga or Al) which undergoes the 1attice relaxation. The observed persistent increase in mobility is also explained in terms of the two different capture barriers.
10
Content available remote

Influence of Substrate on Crystallographic Quality of AlGaN/GaN HEMT Structures Grown by Plasma-Assisted MBE

45%
Wierzbicka A., Żytkiewicz Z., Sobańska M., Kłosek K., Łusakowska E.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 4
899-902
EN
Results of characterization of AlGaN/GaN high electron mobility transistor (HEMT) structures grown by plasma-assisted molecular beam epitaxy (PAMBE) are reported. High resolution X-ray diffraction (HRXRD) and X-ray reflectivity (XRR) were applied to show that structural properties of the AlGaN/GaN layers strongly depend on the substrate used for growth. It has been found that an additional 10 μm thick HVPE GaN layer grown on a commercial GaN/sapphire substrate significantly improves structural quality of AlGaN layer. However, the best structural parameters have been obtained for the HEMT sample grown on free-standing HVPE bulk GaN substrate.
11
Content available remote

AlGaAs to GaAs Energy Transfer Mechanisms in AlGaAs/GaAs Structures

45%
Karpińska K., Godlewski M., Żytkiewicz Z., Chen W., Weber E.
Acta Physica Polonica A
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1992
|
vol. 82
|
issue 4
713-716
EN
The results of photoluminescence and optically detected cyclotron resonance experiments are presented for thick AlGaAs epilayers grown by liquid phase electroepitaxy method on GaAs:Cr substrate. These results indicate an efficient energy transfer from excited AlGaAs to GaAs.
12
Content available remote

Formation of the DX State by Donors in Al_{x}Ga_{1-x}As - Experiment

39%
Dobaczewski L., Kaczor P., Missous M., Żytkiewicz Z., Dobosz D., Peaker A.
Acta Physica Polonica A
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1992
|
vol. 82
|
issue 5
905-907
EN
A high-resolution Laplace-transform deep level transient spectroscopy was used to study electron emission from the DX centres related to group IV and VI donor elements in AlGaAs. This provides the experimental evidence that substitutional-interstitial atom motion is responsible for DX behaviour and for the associated metastability effects.
13
Content available remote

The Impact of Bulk Defects, Surface States, and Excitons on Yellow and Ultraviolet Photoluminescence in GaN

39%
Matys M., Miczek M., Adamowicz B., Żytkiewicz Z., Kamińska E., Piotrowska A., Hashizume T.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 6A
A-73-A-75
EN
The quantitative analysis of the influence of deep bulk levels, surface states and excitons on yellow, green and ultraviolet photoluminescence from n-type GaN was performed. The theoretical calculations of recombination rates in the bulk and at n-GaN surface versus UV-excitation intensity were done numerically using finite element method basing on drift-diffusion model assuming point deep levels, continuous energetic distribution of surface states, as well as excitons. The obtained results of the photoluminescence intensity were compared with experimental data (measured within the range from 10^{15} to 10^{19} photon cm^{-2} s^{-1}) for n-GaN samples with various surface passivating layers (Al_2O_3, SiO_2).
14
Content available remote

Lattice Sites of Silicon Impurities in AlGaAs Grown by Liquid Phase Epitaxy

39%
Kaczor P., Ashwin M., Dobosz D., Żytkiewicz Z., Newman R., Dobaczewski L.
|
EN
Localised vibrational mode infrared absorption (10 K) and Hall measurements were made on a series of Si doped Al_{x}Ga_{1-x}As samples with 0 ≤ x ≤ 0.25 grown by liquid phase epitaxy. Localised vibrational modes were detected from Si_{Ga} donors, Si_{As} acceptors and Si_{Ga}-Si_{As} pairs which increased in frequency as x increased. The assignments of new lines observed at 386, 388 and 391 cm^{-1} are discussed in relation to possible perturbations of the lines from Si_{Ga} or Si_{As}. The presence of DX centres was inferred from observed persistent photoconductivity and attempts were made to relate this result to the presence of the new IR lines.
15
Content available remote

Optical and Electrical Studies of Graphene Deposited on GaN Nanowires

33%
Kierdaszuk J., Kaźmierczak P., Drabińska A., Wysmołek A., Korona K., Kamińska M., Pakuła K., Pasternak I., Krajewska A., Żytkiewicz Z.
|
|
vol. 126
|
issue 5
1087-1089
EN
In this paper using scanning electron microscope, contactless microwave electronic transport and the Raman spectroscopy we studied the properties of graphene deposited on GaN nanowires and compared it with the graphene deposited on GaN epilayer. The Raman micro-mapping showed that nanowires locally change the strain and the concentration of carriers in graphene. Additionally we observed that nanowires increase the intensity of the Raman spectra by more than one order of magnitude.
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