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1

Experimental Study of Optical Transitions in Be-Doped GaAs/AlAs Multiple Quantum Wells

100%

Kundrotas J., Čerškus A., Ašmontas S., Valušis G., Sherliker B., Halsall M., Harrison P., Steer M.

Acta Physica Polonica A

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2005

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vol. 107

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issue 2

245-249

EN

We present a photoluminescence study of optical transitions in Be acceptor-doped GaAs/AlAs multiple quantum wells at room and liquid nitrogen temperatures. We investigate excitonic spectra and reveal acceptor-impurity induced effects in multiple quantum wells having different width.

2

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.

3

Normal Incidence Mid-Infrared Photocurrent in AlGaN/GaN Quantum Well Infrared Photodetectors

81%

Sherliker B., Halsall M., Harrison P., Jovanović V., Indjin D., Ikonić Z., Parbrook P., Whitehead M., Wang T., Buckle P., Phillips J., Carder D.

Acta Physica Polonica A

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2005

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vol. 107

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issue 1

174-178

EN

We report the growth and characterization of AlGaN/GaN multiple quantum well structures designed to have intersubband transitions in the mid-infrared region of the spectrum. The samples were nominally undoped but were found to contain a high electron population in the wells induced by the local polarization fields. The sample was characterized by the use of the Raman spectroscopy and photocurrent spectroscopy. The Raman spectroscopy shows electronic Raman scattering from intersubband transitions in the AlGaN/GaN quantum wells. The e_1-e_2 and e_1-e_3 transitions of the confined 2d electron population in the wells can clearly be observed. A sample designed to absorb at 4μm was fabricated into mesa structures and the vertical photocurrent measured under normal incidence illumination from the free-electron laser FELIX. A wavelength and bias dependent photocurrent was observed in the mid-IR region of spectrum. The peak responsivity was of the order of 50μA/W at 4 K, the photocurrent still being measurable at room 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

|

2005

|

vol. 107

|

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

1 2008

3 2005

4 Halsall M.

4 Harrison P.

4 Sherliker B.

3 Valušis G.

2 Kavaliauskas J.

2 Krivaitė G.

2 Seliuta D.

2 Steer M.

2 Čechavičius B.

1 Ašmontas S.

1 Balakauskas S.

1 Buckle P.

1 Carder D.

1 Devenson J.

1 Grigelionis I.

1 Ikonić Z.

1 Indjin D.

1 Jovanović V.

1 Khanna S.

1 Kundrotas J.

1 Lachab M.

1 Linfield E.

1 Parbrook P.

1 Phillips J.

1 Wang T.

1 Whitehead M.

1 Čerškus A.

1 Širmulis E.

Experimental Study of Optical Transitions in Be-Doped GaAs/AlAs Multiple Quantum Wells

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

Normal Incidence Mid-Infrared Photocurrent in AlGaN/GaN Quantum Well Infrared Photodetectors

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