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1

Photoreflectance of Epitaxial InGaAs Quantum Rods

100%

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.

2

Energy Spectrum of InAs Quantum Dots in GaAs/AlAs Superlattices

100%

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.

3

Terahertz Detection with δ-Doped GaAs/AlAs Multiple Quantum Wells

81%

Seliuta D., Čechavičius B., Kavaliauskas J., Krivaitė G., Grigelionis I., Balakauskas S., Valušis G., Sherliker B., Halsall M., Lachab M., Khanna S., Harrison P., Linfield E.

Acta Physica Polonica A

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2008

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vol. 113

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issue 3

909-912

EN

The authors demonstrate selective detection of terahertz radiation employing berylliumδ-doped GaAs/AlAs multiple quantum wells. The sensitivity up to 1 V/W within 4.2-7.3 THz range at liquid helium temperatures is reached. The Franz-Keldysh oscillations observed in photo- and electroreflectance spectra allowed one to estimate built-in electric fields in the structures studied. It was found that the electric field strength in the cap layer region could vary from 10 kV/cm up to 26 kV/cm, depending on the structure design and temperature.

4

Optical and Terahertz Characterization of Be-Doped GaAs/AlAs Multiple Quantum Wells

81%

Čechavičius B., Kavaliauskas J., Krivaitė G., Seliuta D., Širmulis E., Devenson J., Valušis G., Sherliker B., Halsall M., Steer M., Harrison P.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

328-332

EN

We report on optical, photoreflectance and surface photovoltage, as well as terahertz photocurrent investigation of Be-doped GaAs/AlAs multiple quantum wells at room and liquid helium temperatures, respectively. From the Franz-Keldysh oscillations observed in photoreflectance spectra we determine built-in electric fields within the structure. Interband transition energies calculated by the transfer matrix method are in qualitative agreement with experimentally determined values for the samples having various, from 2×10^{10} up to 2.5×10^{12} cm^{-2}, Be doping densities. The photocurrent observed in the range of 5.4-7.3 THz we associate with photoionization of Be-acceptor states.

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4 Acta Physica Polonica A

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4 Kavaliauskas J.

4 Valušis G.

4 Čechavičius B.

3 Krivaitė G.

2 Halsall M.

2 Harrison P.

2 Karpus V.

2 Khanna S.

2 Linfield E.

2 Nedzinskas R.

2 Seliuta D.

2 Sherliker B.

1 Balakauskas S.

1 Devenson J.

1 Grigelionis I.

1 Lachab M.

1 Li L.

1 Schrey F.

1 Steer M.

1 Strasser G.

1 Tamošiūnas V.

1 Unterrainer K.

1 Širmulis E.

Photoreflectance of Epitaxial InGaAs Quantum Rods

Energy Spectrum of InAs Quantum Dots in GaAs/AlAs Superlattices

Terahertz Detection with δ-Doped GaAs/AlAs Multiple Quantum Wells

Optical and Terahertz Characterization of Be-Doped GaAs/AlAs Multiple Quantum Wells