http://dspace.nbuv.gov.ua:80/handle/123456789/114622 Sun, 05 Apr 2026 19:32:18 GMT 2026-04-05T19:32:18Z http://dspace.nbuv.gov.ua:80/bitstream/id/341313/ http://dspace.nbuv.gov.ua:80/handle/123456789/114622 http://dspace.nbuv.gov.ua:80/handle/123456789/120510 Photoresponse of Schottky-barrier detector under strong IR laser excitation Asmontas, S.; Seliuta, D.; Sirmulis, E. Peculiarities of the photovoltaic effect in Ti/n-Si Schottky contact have been studied experimentally under infrared (IR) laser excitation at wavelengths 2.79, 3, 5, 7 and 10.6 mm. We demonstrate that strong laser excitation gives rise to the photovoltage even if an incident photon energy is lower than Schottky barrier height. In this case the photovoltage as a function of light intensity follows a power-law dependence with the power greater than unity (2...6). The results are interpreted from the viewpoint of electron emission over the potential barrier due to multiphoton or multistep light absorption at the metal-semiconductor interface. Sat, 01 Jan 2000 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120510 2000-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/120509 Pseudomorphic modulation-doped AlGaAs/InGaAs/GaAs heterostructures with strong manifestation of many-body effects Masselink, W.T.; Kissel, H.; Mueller, U.; Walther, C.; Mazur, Yu.I.; Tarasov, G.G .; Rudko, G.Yu.; Valakh, M.Ya.; Malyarchuk, V.; Zhuchenko, Z.Ya. Photoluminescence (PL) study of pseudomorphic heavily modulation-doped AlxGa₁₋xAs/InyGa₁-yAs/GaAs heterostructures shows fundamental changes in the PL spectrum under excitation pumping and/or temperature increase. In most the high and low energy tails of the PL feature undergo the principal transformations. High-energy tail peculiarities are related to the repelling of the Fermi-edge singularity (FES) and the excitonic states. The character of repelling depends crucially on the excitation density and/or temperature. At low temperature the origination of the FES feature has been observed for the first time under increasing the excitation density. The FES appearance is accompanied by the formation of an abrupt high energy edge and occurs far below by intensity the hybridized n = 2 exciton manifestation. Strong screening of the n = 2 exciton state by photoexcited carriers is observed, resulting in the 2D electron gas-heavy hole recombination for the second electron subband. The many-body feature is detected in the magnetoluminescence spectrum. This feature develops in magnetic field B = 7 T at low temperature (T = 4.2 K) and is surely detected up to T ≈ 50 K. The LO-phonon side bands for the parent transitions between the Landau levels (LL's) are revealed in the low-energy tail of the PL spectra in magnetic field. The evolution of these phonon side-band with temperature and excitation density is observed. The enhanced strength of phonon side-bands is attributed to an enhanced Frohlich coupling with account of confined phonon and interface modes. Sat, 01 Jan 2000 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120509 2000-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/120508 InAs quantum dots embedded into anti-modulation-doped GaAs superlattice structures Masselink, W.T.; Kissel, H.; Mueller, U.; Walther, C.; Mazur, Yu.I.; Tarasov, G.G.; Lisitsa, M.P.; Lavoric, S.R.; Zhuchenko, Z.Ya. Photoluminescence (PL) spectra of anti-modulation-doped GaAs superlattice structures containing thin InAs films of about 1-2.5 monolayers grown on semi-insulating (001)-oriented GaAs substrates at different temperatures are studied. The size distribution of InAs quantum dots (QD's) is found to be bimodal at the higher substrate growth temperature (TG = 505 °C) and is transformed into multimodal for the decreased growth temperature (TG = 420 °C) and growth interruption applied. For the first time we demonstrate the strong coupling between modes, which stabilizes the PL magnitude and the full width at half maximum of large index QD modes within a certain temperature interval (50-150 K) due to feeding of the radiative transitions from non-radiative decay and carrier transfer arising from decaying excitonic states of the low index QD mode. Sat, 01 Jan 2000 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120508 2000-01-01T00:00:00Z http://dspace.nbuv.gov.ua:80/handle/123456789/120507 Excitonic effects in band-edge luminescence of semiconductors at room temperatures Sachenko, A.V.; Kryuchenko, Yu.V. A theoretical analysis is developed for ascertaining the influence of exciton states on edge luminescence in different semiconductors at high temperatures and high levels of excitation. Screening effects and the Mott transition for excitons have been taken into account using simple relations obtained with a variational method. Dependencies of luminescence quantum efficiency on excitation level are discussed. A mechanism of exciton non-radiative annihilation due to Auger recombination via deep impurity levels is analysed as well. It is shown that the probability of this process decreases with an energy of exciton binding. Sat, 01 Jan 2000 00:00:00 GMT http://dspace.nbuv.gov.ua:80/handle/123456789/120507 2000-01-01T00:00:00Z