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1

Photo-ESR and Absorption Studies of Antisite Defects in GaP

100%

Palczewska M., Jasiński J., Kamińska M.

Acta Physica Polonica A

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1995

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vol. 87

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issue 2

461-464

EN

Photo-ESR and optical absorption measurements were done on annealed neutron irradiated GaP crystals. The position of paramagnetic gallium anti-site level in GaP energy gap has been determined. Additionally, the position of paramagnetic phosphorus antisite level, earlier determined in the paper of Kruger and Alexander, has been confirmed. Moreover, unusual in ESR experiments temperature dependence of phosphorus antisite amplitude in neutron irradiated GaP crystals has been explained.

2

Antisites Defects in GaP

100%

Jasiński J., Kamińska M., Palczewska M., Jurkiewicz-Wagner P.

Acta Physica Polonica A

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1993

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vol. 84

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issue 3

579-582

EN

ESR, optical, and transport measurements were done on neutron-irradiated GaP crystals subjected to thermal annealing. The behavior of two dominant paramagnetic defects: phosphorus antisite PP4 and WA1 [1] was followed. ESR signal similar to WA1 was earlier attributed to the defect related with gallium antisite [2]. Our thermal annealing experiments supported such attribution. Apart from that, the obtained results indicated that two dominant absorption bands in neutron-irradiated GaP with maxima at 0.79 and 1.13 eV [1] were not connected with PP_{4} or WA1 defects. However, one of these paramagnetic defects (or two of them) were responsible for hopping transport in n-irradiated GaP crystals.

3

Nature of Donors in SiC

88%

Suchanek B., Dwiliński R., Kamińska M., Palczewska M., Vlaskina S.

Acta Physica Polonica A

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1995

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vol. 87

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issue 2

321-324

EN

6H-SiC samples were examined by ESR technique in temperature range from 5 K up to 300 K. Two kinds of ESR lines were observed: a single line at g = 2.0054 ± 0.0007, called X-line, and a triplet corresponding to isolated nitrogen defect. Ionization energy of X defect was determined as about 60 meV and the ionization energy of isolated nitrogen was determined as about 200 meV below SiC conduction band.

4

Electrical and ESR Studies of GaN Layers Grown by Metal Organic Chemical Vapour Deposition

88%

Suchanek B., Palczewska M., Pakuła K., Baranowski J., Kamińska M.

Acta Physica Polonica A

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1997

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vol. 92

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issue 5

1001-1004

EN

Electrical transport and ESR studies were performed on the state-of-theart GaN layers grown on sapphire substrate using metal organic chemical vapour deposition technique. For undoped samples electron concentration below 2×10^{17} cm^{-1} and mobility up to 500 cm^{2}/(V s) were achieved whereas hole concentration up to 7×10^{17} cm^{-3} and mobility about 16 cm^{2}/(V s) were obtained for intentionally Mg doped samples and subsequently annealed. Temperature dependence of mobility was discussed. ESR revealed the presence of two resonance absorption lines. One of them with g_{⊥}=1.9487 and g_{∥}=1.9515, commonly observed in n-type GaN was due to shallow donor. The second ESR line was an isotropic one of g=2.0032 and it is discussed.

5

Defects Studies in As Grown and Neutron Irradiatcd Phosphorus Rich GaP

76%

Jasiński J., Palczewska M., Korona K., Kamińska M., Bourret E., Elliot G.

Acta Physica Polonica A

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1992

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vol. 82

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issue 5

829-832

EN

Semi-insulating, p- and n-type liquid encapsulated Czochralski grown phosphorus rich GaP crystals before and alter neutron irradiation were studied. EPR measurements proved that the phosphorus antisite defect P_{Ga} introduced by neutron irradiation was exactly the same as in as grown materials, i.e. surrounded by four substitutional phosphorus atoms. In neutron irradiated crystals EPR showed also a signal, similar to the one found in plastically deformed GaAs and GaP. The concentrations of P_{Ga} and of the other defect were estimated to be of the same order of magnitude. Two absorption bands at 0.81 and 1.12 eV were found for irradiated materials. The temperature dependence of resistivity indicated hopping as the mechanism of conduction in samples irradiated with doses higher than 4 × 10^{16} cm^{-2}.

6

Optical and Electrical Studies of FR1 and FR2 Defects in GaAs

76%

Dwiliński R., Palczewska M., Kaczor P., Korona K., Wysmołek A., Bożek R., Kamińska M.

Acta Physica Polonica A

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1992

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vol. 82

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issue 4

613-616

EN

The systematic EPR, optical absorption, photoluminescence and thermally stimulated current studies of acceptor defects in bulk GaAs were performed. For the first time, parallel EPR and optical absorption experiments allowed to find the absorption spectrum due to the photoionization of FR1 defect with the threshold at 0.19 eV. Photoluminescence studies showed two families of bands in the energy range of about 1.25 to 1.35 eV. We tentatively ascribed them to FR1 and FR2 complexes with shallow donors. Thermally stimulated current measurements showed two peaks at 90 K and 110 K assigned to FR1 and FR2 respectively.

7

Electrical and Optical Properties of Highly Non-stoichiometric GaAs

76%

Kurpiewski A., Korona K., Kamińska M., Palczewska M., Jagadish C., Williams J.

Acta Physica Polonica A

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1995

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vol. 87

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issue 2

518-522

EN

The studies of transport and optical properties of GaAs implanted with high arsenic doses were performed. As-implanted samples showed hopping conductivity and the exponential absorption tail in the near-IR region. Both effects were probably caused by the amorphization of implanted layer. Using EPR measurements it was found that arsenic antisite defect with high local strain field was created during implantation. Annealing of implanted layers at 600°C led to substantial removal of amorphization, decrease in absorption coefficient and hopping conductivity leading to resistive samples. The possible model of such behaviour may be similar to the one of suggested for low temperature GaAs layers.

8

Some Optical and Epr Properties of Strain-Free GaN Crystals Obtained by Ammono Method

76%

Dwiliński R., Baranowski J. M., Kamińska M., Doradziński R., Garczyński J., Sierzputowski L., Palczewska M.

Acta Physica Polonica A

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1997

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vol. 92

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issue 4

737-741

EN

AMMONO GaN is grown spontaneously from ammonia solution in form of regular, well shaped, few micrometer crystals. Photoluminescence spectra of these crystals are characterized by fixed positions of very narrow exciton lines (FWHM down to 1 meV), where free excitons A, B, C, resolved two donor bound excitons and acceptor bound exciton are visible. Fixed position of exciton lines is in contrast to small changes of line energies which have been always observed for epitaxial GaN layers because of strain present in them. Free electron concentration of AMMONO GaN is less than few times 10^{15} cm^{-3}, as estimated from EPR signal of shallow donor. The above-mentioned facts qualified these crystals as state of the art strain-free, model material for basic parameter measurements of GaN. In this work, results of PL and EPR measurements performed on AMMONO GaN crystals are presented and discussed.

9

Mn Impurity in Bulk GaAs Crystals

64%

Pawłowski M., Piersa M., Wołoś A., Palczewska M., Strzelecka G., Hruban A., Gosk J., Kamińska M., Twardowski A.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

825-830

EN

Magnetic and electron transport properties of GaAs:Mn crystals grown by Czochralski method were studied. Electron spin resonance showed the presence of Mn acceptor A in two charge states: singly ionized A^- in the form of Mn^{2+}(d^5), and neutral A^0 in the form of Mn^{2+}(d^5) plus a bound hole (h). It was possible to determine the relative concentration of both types of centers from intensity of the corresponding electron spin resonance lines. Magnetization measured as a function of magnetic field (up to 6 T) in the temperature range of 2-300 K revealed overall paramagnetic behavior of the samples. Effective spin was found to be about 1.5 value, which was consistent with the presence of two types of Mn configurations. In most of the studied samples the dominance of Mn^{2+}(d^5)+h configuration was established and it increased after annealing of native donors. The total value of Mn content was obtained from fitting of magnetization curves with the use of parameters obtained from electron spin resonance. In electron transport, two mechanisms of conductivity were observed: valence band transport dominated above 70 K, and hopping conductivity within Mn impurity band at lower temperatures. From the analysis of the hopping conductivity and using the obtained values of the total Mn content, the effective radius of Mn acceptor in GaAs was estimated as a = 11±3Å.

10

Superconductivity in Indium Diffused GaAs

64%

Baranowski J., Wójcik P., Palczewska M., Jabłoński R., Weber E., Yau W., Sohn H., Werner P.

Acta Physica Polonica A

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1992

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vol. 82

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issue 4

670-673

EN

Superconductivity of indium diffused GaAs was investigated. The superconductivity in these samples was identified by the magnetic susceptibility and the characteristic field modulated microwave absorption. The static magnetic susceptibility was measured from 40 K down to 2.5 K. The result shows two distinctive diamagnetic contributions within 7 K-2.5 K range. These diamagnetic contributions were correlated with the excess of In and Ga metal in GaAs.

11

Photoluminescence and Electron Paramagnetic Resonance Studies of Bulk GaN Doped with Gadolinium

64%

Lipińska Z., Pawłowski M., Żołnierowicz H., Wysmołek A., Palczewska M., Kamińska M., Twardowski A., Boćkowski M., Grzegory I.

Acta Physica Polonica A

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2006

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vol. 110

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issue 2

243-248

EN

Photoluminescence and electron paramagnetic resonance experiments on strain free GaN bulk crystals of wurtzite structure doped with gadolinium are reported. Efficient gettering of residual GaN donors by Gd was observed. Electron paramagnetic resonance showed that Gd ion incorporated into GaN lattice had Gd^{3+}(4f^7) configuration. The observed photoluminescence spectra were explained as due to intracenter Gd^{3+}(4f^7) transitions. No ferromagnetic behavior was detected.

12

Mn Impurity in GaN Studied by Electron Paramagnetic Resonance

64%

Wołoś A., Palczewska M., Wilamowski Z., Kamińska M., Twardowski A., Boćkowski M., Grzegory I., Porowski S.

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EN

We present the results of electron paramagnetic resonance investigations of GaN bulk crystals doped with Mn. The EPR experiment shows the Mn^{2+} resonance in all the investigated n-type crystals, while in highly resistive samples extra doped with Mg acceptor the Mn^{2+} resonance decreases. This is a consequence of the location of Mn acceptor level in GaN band gap. The analysis of the spin relaxation times reveals the Korringa scattering as the dominating spin relaxation mechanism in n-type GaN:Mn crystals. The effective exchange constant determined from spin relaxation rate temperature dependence is of the order of 14 meV.

13

Formation of Mn-Related Defect Band in InP

52%

Macieja B., Korona K., Piersa M., Witowski A., Wasik D., Wysmołek A., Strzelecka G., Hruban A., Surma B., Palczewska M., Kamińska M., Twardowski A.

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EN

Electron paramagnetic resonance, optical absorption, luminescence and electrical studies of InP highly doped with Mn were performed. Electron paramagnetic resonance revealed presence of manganese in Mn^{2+}(d^5) configuration. In optical absorption, systematic reduction of InP band gap was observed with increase in Mn content. This was correlated with increase in photoionization-type absorption band starting at 0.2 eV. Time-resolved photoluminescence measurements showed decrease in photoexcited carrier lifetime and shortening of donor-acceptor pair recombination time with increase in Mn content. Moreover, photoluminescence band was shifted to lower energies, similarly to optical band gap. In electrical transport two mechanisms of conductivity were observed. Valence band transport dominated at higher temperatures, above 160 K, and activation energy of free-hole concentration was determined as about 0.20 eV. At lower temperatures hopping conductivity, clearly related to Mn defect band, was present. All these results were consistent with assumption of creation of Mn-related defect-band at 0.2 eV above InP valence band. It was found that Mn centers responsible for this band were in configurations of either d^5 or d^5 plus a hole localized about 7Å around corresponding Mn core.

Refine search results

Photo-ESR and Absorption Studies of Antisite Defects in GaP

Antisites Defects in GaP

Nature of Donors in SiC

Electrical and ESR Studies of GaN Layers Grown by Metal Organic Chemical Vapour Deposition

Defects Studies in As Grown and Neutron Irradiatcd Phosphorus Rich GaP

Optical and Electrical Studies of FR1 and FR2 Defects in GaAs

Electrical and Optical Properties of Highly Non-stoichiometric GaAs

Some Optical and Epr Properties of Strain-Free GaN Crystals Obtained by Ammono Method

Mn Impurity in Bulk GaAs Crystals

Superconductivity in Indium Diffused GaAs

Photoluminescence and Electron Paramagnetic Resonance Studies of Bulk GaN Doped with Gadolinium

Mn Impurity in GaN Studied by Electron Paramagnetic Resonance

Formation of Mn-Related Defect Band in InP