Results found: 3

Number of results on page

Search results

Sort By:

Limit search:

Time-Resolved Transient Grating Spectroscopy for Studies of Nonequilibrium Carrier Dynamics in Wide Band-Gap Semiconductors

100%

Jarašiūnas K., Malinauskas T., Neimontas K., Gudelis V., Aleksiejūnas R.

Acta Physica Polonica A

2006

vol. 110

issue 2

201-209

Using interdisciplinary fields relevant to a highly excited semiconductor - nonequilibrium phenomena in high density plasma, light-induced changes of optical properties, and dynamic holography, we developed time-resolved four-wave mixing technique for monitoring the spatial and temporal carrier dynamics in wide band-gap semiconductors. This opened a new possibility to analyse fast electronic processes in a non-destructive "all-optical" way, i.e. without any electrical contacts. This technique allowed evaluation of recombination and transport processes and the determination of important carrier parameters which directly reveal the material quality: carrier lifetime, bipolar diffusion coefficients, surface recombination rate, nonlinear recombination rate, diffusion length, threshold of stimulated recombination. The recent experimental studies of differently grown group III-nitrides (heterostructures and free standing films) as well silicon carbide epilayers by nondegenerate picosecond four-wave mixing are presented.

High-Speed Quadratic Electrooptic Nonlinearity in dc-Biased InP

100%

Subačius L., Kašalynas I., Vingelis M., Aleksiejūnas R., Jarašiūnas K.

Acta Physica Polonica A

2005

vol. 107

issue 2

280-285

We present experimental data on degenerate four-wave mixing as well as simulation results of fast optical nonlinearities in highly-excited semi-insulating InP under applied dc-field. Hot-electron transport governed enhancement of optical nonlinearity is obtained by applying a dc-field of 10-14 kV/cm at full-modulation depth of a light-interference pattern. The hydrodynamic model, which incorporates both free-carrier and photorefractive nonlinearities is used to explain the experimentally observed features. We show that the enhancement of optical nonlinearity is due to the quadratic electrooptic effect.

Transients of Carrier Recombination and Diffusion in Highly Excited GaN Studied by Photoluminescence and Four-Wave Mixing Techniques

73%

Juršėnas S., Miasojedovas S., Kurilčik G., Žukauskas A., Aleksiejūnas R., Malinauskas T., Sūdžius M., Jarašiūnas K.

Acta Physica Polonica A

2005

vol. 107

issue 2

240-244

Time-resolved photoluminescence and four-wave mixing techniques have been combined for studies of carrier relaxation dynamics in a highly photoexcited GaN epilayer. For a moderate excitation density below 1 mJ/cm^2, carrier recombination was due to free carrier capture by deep traps. The characteristic time of carrier capture,τ_e=550 ps, was measured under deep trap saturation regime. The ambipolar diffusion coefficient for free carriers, D=1.7 cm^2/s, was estimated from the analysis of the transients of the light-induced gratings of various periods. A complete saturation of the four-wave mixing efficiency was observed for the excitation energy density exceeding 1.5 mJ/cm^2. The latter saturation effect was shown to be related to electron-hole plasma degeneration, which results in a significant enhancement of carrier recombination rate due to onset of stimulated emission.

Refine search results

3 Acta Physica Polonica A

1 2006

2 2005

3 Aleksiejūnas R.

3 Jarašiūnas K.

2 Malinauskas T.

1 Gudelis V.

1 Juršėnas S.

1 Kašalynas I.

1 Kurilčik G.

1 Miasojedovas S.

1 Neimontas K.

1 Subačius L.

1 Sūdžius M.

1 Vingelis M.

1 Žukauskas A.

Search results

Time-Resolved Transient Grating Spectroscopy for Studies of Nonequilibrium Carrier Dynamics in Wide Band-Gap Semiconductors

High-Speed Quadratic Electrooptic Nonlinearity in dc-Biased InP

Transients of Carrier Recombination and Diffusion in Highly Excited GaN Studied by Photoluminescence and Four-Wave Mixing Techniques