| 1. |
- Grivickas, V., et al.
(författare)
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Strong photoacoustic pulses generated in TlGaSe2 layered crystals
- 2008
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Ingår i: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY. - : IOP Publishing.
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Konferensbidrag (refereegranskat)abstract
- Periodic deflections of infrared probe beam in TlGaSe2 crystal after its lateral excitation by laser pulse with photon energy near the band gap are observed. Such deflections arise from travelling of the acoustic pulse within sample which, in turn, is produced by optical pump pulse through photoacoustic effect. The photoacoustic pulse is generated within thin region near the crystal excited face, much shorter then the light penetration depth. In the case of volume excitation photoacoustic pulse is also generated in the region near back face as well. Tentative explanation of the generation mechanism is discussed.
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| 2. |
- Bikbajevas, V, et al.
(författare)
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Impact of phonon drag effect on Seebeck coefficient in p-6H-SiC : Experiment and simulation
- 2003
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Ingår i: Materials Science Forum, Vols. 433-436. ; , s. 407-410
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Konferensbidrag (refereegranskat)abstract
- The temperature dependence of Seebeck coefficient (S) for p-6H-SiC has been obtained. It increases from 2 up to 5.2 mV/K when temperature decreases from 400 down to 240 K. It is shown that phonon drag effect makes critical contribution to the S value. Improved theoretical model involving 4-phonon scattering process has been proposed for the simulation of Seebeck coefficient phonon pail.
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| 3. |
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| 4. |
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| 5. |
- Grivickas, V., et al.
(författare)
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Spatially and time-resolved infrared absorption for optical and electrical characterization of indirect band gap semiconductors
- 2000
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Ingår i: Thin Solid Films. - 0040-6090 .- 1879-2731. ; 364:02-jan, s. 181-185
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Tidskriftsartikel (refereegranskat)abstract
- The current status of the spatially and time-resolved free-carrier absorption (FCA) method is provided. The FCA technique allows monitoring carrier dynamics in a time scale from nanoseconds to miliseconds by employing either collinear or orthogonal geometry between pump and probe beams. A high spatial resolution is achieved allowing in-depth carrier profiles to be extracted. The method is particularly suited for investigation of injection-dependent optical and recombination phenomena: band gap optical absorption, Shockley-Read-Hall (SRH) lifetime, Auger recombination coefficient, and the injection-dependent surface (interface) recombination velocity. We summarize important aspects of the technique demonstrating numerous measurements that have been implemented in studies of bulk Si, epilaxial 4H-SiC and porous silicon.
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| 6. |
- Grivickas, V, et al.
(författare)
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Thermopower measurements in 4H-SiC and theoretical calculations considering the phonon drag effect
- 2001
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Ingår i: Materials Science Forum, Vols. 353-356. ; , s. 491-494
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Konferensbidrag (refereegranskat)abstract
- The Seebeck coefficient study in a heavily nitrogen-doped n-type 4H-SiC epilayer in the direction perpendicular to c-axis is presented. The Seebeck coefficient steeply increases from 0.56 mV/K to 1.7 mV/K with decreasing temperature in the range 400-80 R. This behavior is explained by the phonon drag effect. An approach to the theoretical modeling of the phonon drag effect is discussed and simulation of the Seebeck coefficient temperature-dependence is displayed.
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| 7. |
- Grivickas, V., et al.
(författare)
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Two-photon indirect absorption in GaSe
- 2008
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Ingår i: PROCEEDINGS OF THE 17TH INTERNATIONAL VACUUM CONGRESS/13TH INTERNATIONAL CONFERENCE ON SURFACE SCIENCE/INTERNATIONAL CONFERENCE ON NANOSCIENCE AND TECHNOLOGY. - : IOP Publishing.
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Konferensbidrag (refereegranskat)abstract
- Two-photon absorption (TPA) in GaSe is detected in the narrow (about kT) spectral range above the indirect exciton energy for E⊥c light polarization. The appearance of TPA enhancement within narrow spectral region links to the resonant Raman scattering and anti-Stockes photoluminescence previously identified in GaSe. Extracted TPA coefficient is of the order of 10 cm/W and 5-10 times exceeds ones obtained previously for lower quanta energies.
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