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1

Quasi Fermi Levels in Semiconductor Photovoltaic Heterojunction

100%

Orlowski B., Pieniazek A., Goscinski K., Kopalko K.

Acta Physica Polonica A

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2016

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vol. 129

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issue 1a

A-100-A-102

EN

The photovoltaic heterojunction elements are build of two different semiconductors of n and p type. Under cell illumination the same density of n and p carriers are created in each generation point but it leads to the remarkably higher increase of relative concentration for minority than for majority carriers. It is causing bigger energy change of the quasi Fermi level of minority than of majority carriers. The minority carriers decide of the value of generated photovoltage while the majority carriers contribution to it, in most cases can be neglected. Measured change of the generated open circuit photovoltage versus illumination light intensity allows to estimate corresponding to it increase of the minority carrier concentration. These allows as well to scan the part of the forbidden gap region by the minority carriers quasi Fermi level and in a case of impurity or defect levels located in forbidden gap it can influence on the continuous dependence of generated photovoltage versus light intensity e.g. for pinning of the Fermi level. To create efficient photovoltaic heterojunction it will need to study electronic properties of the used impurities and their proper distribution in the region of junction.

2

Photoemission Electronic Spectra οf CdTe/Pb_{0.95}Eu_{0.05}Te/CdTe

76%

Orlowski B., Dziawa P., Gas K., Reszka A., Mickievicius S., Thiess S., Drube W.

Acta Physica Polonica A

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2011

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vol. 120

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issue 5

960-963

EN

The synchrotron radiation was used to apply tunable high energy X-ray photoemission spectroscopy for investigation of electronic structure of semiconductor nanostructure CdTe/Pb_{0.95}Eu_{0.05}Te/CdTe/GaAs(001) top part. The Pb_{0.95}Eu_{0.05}Te (6 nm thick) was buried under thin (22 nm) top layer of CdTe transparent for part of electrons photoemitted from Pb_{0.95}Eu_{0.05}Te buried layer. The top layer of CdTe was sputtered by Ar ion bombardment for surface cleaning and for leaving the thickness of CdTe more transparent for photoelectrons emitted from buried layer. For these thickness of the top layer the photoemission energy distribution curves corresponding to the valence band and core levels electrons of the buried layer atoms were measured with application of synchrotron radiation of energy hν = 3510 eV. The measured spectra corresponding to the buried layer atoms were observed in the valence band region and in the high binding energy region for core levels of Pb 4f, Pb 3d. The valence band contribution and core levels Cd 4d and Cd 3d were obtained mainly from top cover layer. Measured Te 4d, Te 3d and Te 4d spectra possess contribution as well from top cover layer as from the buried layer. The amount of Eu atoms was to small to be reasonable detected and presented in the paper.

3

Band Structure of Mn/ZnTe Studied, by Angle-Resolved Photoelectron Spectroscopy

76%

Kowalski B., Orlowski B., Pietrzyk M., Kaczor P., Kopalko K., Mickievicius S., Johnson R.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

735-740

EN

The electronic band structure of Mn/ZnTe(110) (1×1) has been studied by angle-resolved photoelectron spectroscopy. The sets of spectra were acquired for the clean surface and after in situ deposition of 0.4 ML of Mn, in order to compare the band structures and to reveal changes brought about by the presence of Mn. The experimental band structure diagram of Mn/ZnTe along theΓ-K direction in the Brillouin zone has been derived from the experimental data. Indications of interaction between the Mn 3d states and sp^3 bands of the semiconductor are discussed.

4

Fano Resonance of Eu^{2+} and Eu^{3+} in (Eu,Gd)Te MBE Layers

64%

Orlowski B., Kowalski B., Dziawa P., Pietrzyk M., Mickievicius S., Osinniy V., Taliashvili B., Kowalik I., Story T., Johnson R.

Acta Physica Polonica A

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2005

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vol. 108

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issue 5

803-807

EN

Resonant photoemission spectroscopy, with application of synchrotron radiation, was used to study the valence band electronic structure of clean surface of (EuGd)Te layers. Fano-type resonant photoemission spectra corresponding to the Eu 4d-4f transition were measured to determine the contribution of 4f electrons of Eu^{2+} and Eu^{3+} ions to the valence band. The resonant and antiresonant photon energies of Eu^{2+} ions were found as equal to 141 V and 132 eV, respectively and for Eu^{3+} ions were found as equal to 146 eV and 132 eV, respectively. Contribution of Eu^{2+}4f electrons was found at the valence band edge while for Eu^{3+} it was located in the region between 3.5 eV and 8.5 eV below the valence band edge.

5

Fano Resonance Investigation of PbTe Layers Containing Eu and Gd Ions

64%

Orlowski B., Osinniy V., Dziawa P., Pietrzyk M., Kowalski B., Taliashvili B., Story T., Johnson R.

Acta Physica Polonica A

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2008

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vol. 114

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issue 2

351-356

EN

The Fano resonance photoemission studies of Gd/(Pb, Gd)Te layers using synchrotron radiation were carried out and the electronic structure parameters like binding energies of Gd^{3+} 4f and 5p shells, resonance and antiresonance energies for Gd^{3+} were determined. The presence of Eu^{3+} ions was observed in the (Pb, Eu)Te and (Eu, Gd)Te layers grown by MBE technique. The comparison of data for (Pb, Gd)Te compound with corresponding data for (Eu, Gd)Te and (Pb, Eu)Te layers indicates that we are not able to distinct the Eu^{3+}4f and Gd^{3+}4f electrons contribution to the valence band photoemission spectra because of small content od Gd and similar binding energy values. The key parameters allowing to prove exactly the presence of either Eu^{3+} or Gd^{3+} are the resonance and antiresonance energies which are significantly different for these ions and equal to 143 eV/137 eV and 150 eV/142 eV, respectively.

6

A Comparison of the Valence Band Structure of Bulk and Epitaxial GeTe-based Diluted Magnetic Semiconductors

64%

Pietrzyk M., Kowalski B., Orlowski B., Knoff W., Story T., Dobrowolski W., Slynko V., Slynko E., Johnson R.

Acta Physica Polonica A

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2010

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vol. 117

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issue 2

293-295

EN

In this work we present a comparison of the experimental results, which have been obtained by the resonant photoelectron spectroscopy for a set of selected diluted magnetic semiconductors based on GeTe, doped with manganese. The photoemission spectra are acquired for the photon energy range of 40-60 eV, corresponding to the Mn 3p → 3d resonances. The spectral features related to Mn 3d states are revealed in the emission from the valence band. The Mn 3d states contribution manifests itself in the whole valence band with a maximum at the binding energy of 3.8 eV.

7

Valence States of Metal Ions in La_{0.7}Ce_{0.3}MnO_3 Thin Films

52%

Mickevičius S., Bondarenka V., Grebinskij S., Oginskis A., Butkutė R., Tvardauskas H., Vengalis B., Orlowski B., Osinniy V., Pietrzyk M., Drube W.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

1071-1074

EN

We report valence states of ions in La_{0.7}Ce_{0.3}MnO_3 thin films grown by a reactive dc magnetron sputtering. The measurements were performed by means of high-energy X-ray photoelectron spectroscopy using synchrotron radiation. It was found that Ce ion in the compound is either in tetravalent or trivalent chemical state, manganese is in divalent, trivalent and tetravalent states, while La ion existing in oxide and hydroxide chemical species is in trivalent state.

Refine search results

Quasi Fermi Levels in Semiconductor Photovoltaic Heterojunction

Photoemission Electronic Spectra οf CdTe/Pb_{0.95}Eu_{0.05}Te/CdTe

Band Structure of Mn/ZnTe Studied, by Angle-Resolved Photoelectron Spectroscopy

Fano Resonance of Eu^{2+} and Eu^{3+} in (Eu,Gd)Te MBE Layers

Fano Resonance Investigation of PbTe Layers Containing Eu and Gd Ions

A Comparison of the Valence Band Structure of Bulk and Epitaxial GeTe-based Diluted Magnetic Semiconductors

Valence States of Metal Ions in La_{0.7}Ce_{0.3}MnO_3 Thin Films