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1

Infrared Reflectance Kramers-Kronig Analysis by Anchor-Window Technique

100%

Tumėnas S., Kašalynas I., Karpus V., Arwin H.

Acta Physica Polonica A

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2011

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vol. 119

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issue 2

140-142

EN

An algorithm for the Kramers-Kronig analysis of the reflectivity spectra, based on an anchor-window technique is presented. The high-frequency asymptote, required for the Kramers-Kronig analysis, is determined by minimizing differences between the Kramers-Kronig-deduced optical constants of a system under investigation and known optical constants measured in a small anchor-window. The algorithm is illustrated by applying it for a reconstruction of the optical conductivity σ(ω) of the fci-ZnMgRE quasicrystals in the spectral range of 0.01-6.5 eV from the experimental IR Fourier-transform reflectivity data and the experimental spectral ellipsometry VIS-UV data. The reliability of the suggested Kramers-Kronig analysis technique is confirmed by independent infrared spectral ellipsometry σ(ω) measurements for fci-ZnMgRE.

2

Optical Response of fci-ZnMgHo Quasicrystal

64%

Karpus V., Babonas G., Rėza A., Suchodolskis A., Tumėnas S., Hunderi O., Assmus W., Brűhne S.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

1005-1008

EN

The results of an optical spectroscopy study of the icosahedral fci-ZnMgHo quasicrystal are presented. The dielectric function of the quasicrystal was measured by the spectroscopic ellipsometry technique in the spectral range of 0.1-5.0 eV. The analysis of the dielectric function shows that an optical response of fci-ZnMgHo is a superposition of the free-electron Drude-type contribution and that of the interband transitions across the fci-ZnMgHo pseudogap.

3

Energy Spectrum of InAs Quantum Dots in GaAs/AlAs Superlattices

64%

Nedzinskas R., Čechavičius B., Kavaliauskas J., Karpus V., Krivaitė G., Tamošiūnas V., Valušis G., Schrey F., Unterrainer K., Strasser G.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

975-978

EN

Photo- and contactless electroreflectance spectroscopies were applied to study optical properties and electronic structure of GaAs/AlAs superlattice systems with embedded InAs quantum dots. The observed interband transitions related to the quantum dot ground and excited states, as well as optical transitions in the combined system formed by the InAs wetting layer and GaAs/AlAs superlattice are discussed.

4

Photoemission and Optical Spectroscopy of i-ZnMgEr Quasicrystal

64%

Suchodolskis A., Assmus W., Babonas G., Giovanelli L., Karlsson U., Karpus V., Le Lay G., Rėza A., Uhrig E.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

412-419

EN

The results of photoemission and optical studies of icosahedral single-grain ZnMgEr quasicrystals are presented. Synchrotron radiation photoemission measurements were performed on in situ cleaved samples at 10^{-10} mbar pressure and low, 140-150 K temperature. The valence band photoemission spectra measured reveal a simple metal-type valence band of icosahedral ZnMgEr with a distinct Fermi edge cut-off and with a sharp pseudogap feature. The photoemission spectra of shallow Mg 2p and Zn 3d core levels indicate a coordination shift of Mg 2p spin-orbit doublet and an oscillating dependence of Zn 3d photoemission line components on the photon energy within the hν=20-160 eV range investigated. The optical response of icosahedral ZnMgEr, a dispersion of the dielectric function, was measured by the spectroscopic ellipsometry technique in the 0.5-5.0 eV spectral range. The optical spectra of the quasicrystal indicate the Drude-type optical response superimposed with a peak of interband optical transitions. The interband optical transitions can be modelled with the pseudogap parameters which agree with those deduced in an analysis of the photoemission valence band spectra.

5

Photoreflectance of Epitaxial InGaAs Quantum Rods

64%

Nedzinskas R., Karpus V., Čechavičius B., Kavaliauskas J., Valušis G., Li L., Khanna S., Linfield E.

Acta Physica Polonica A

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2011

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vol. 119

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issue 2

164-166

EN

Photoreflectance spectroscopy and photoluminescence have been used to study the optical properties and electronic structure of InGaAs quantum rods grown by molecular beam epitaxy. Spectral features associated with interband optical transitions localized in the quantum rod and the surrounding quantum well regions are examined. Experimental results are compared with calculations performed within the envelope function approximation. A red shift of the quantum rod- and a blue shift of the quantum well-related optical transitions, along with a significant increase in PL intensity have been observed if an As_4 source is used instead of an As_2 source during the molecular beam epitaxial growth.

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5 Acta Physica Polonica A

2 2011

2 2008

1 2005

5 Karpus V.

2 Assmus W.

2 Babonas G.

2 Kavaliauskas J.

2 Nedzinskas R.

2 Rėza A.

2 Suchodolskis A.

2 Tumėnas S.

2 Valušis G.

2 Čechavičius B.

1 Arwin H.

1 Brűhne S.

1 Giovanelli L.

1 Hunderi O.

1 Karlsson U.

1 Kašalynas I.

1 Khanna S.

1 Krivaitė G.

1 Le Lay G.

1 Li L.

1 Linfield E.

1 Schrey F.

1 Strasser G.

1 Tamošiūnas V.

1 Uhrig E.

1 Unterrainer K.

Infrared Reflectance Kramers-Kronig Analysis by Anchor-Window Technique

Optical Response of fci-ZnMgHo Quasicrystal

Energy Spectrum of InAs Quantum Dots in GaAs/AlAs Superlattices

Photoemission and Optical Spectroscopy of i-ZnMgEr Quasicrystal

Photoreflectance of Epitaxial InGaAs Quantum Rods