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  1. 64 Acta Physica Polonica A

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  1. 5 Žukauskas A.

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1
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Current-Voltage Characteristic of Semi-Insulating GaAs, with Trap-Filling Effect

100%
Karpińska K., Łusakowski J.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 2-3
281-285
EN
A detailed investigation of current-voltage (I- V)characteristics of semi-insulating GaAs sample was performed in the vicinity of room temperature. The sample with 300 K resistivity of 2 x 10^{7} Ω cm was supplied with guard-ring electrodes which allowed the elimination of surface currents. The observed characteristics started with an ohmic part which was followed by a superlinear current on voltage dependence. At a threshold voltage V_{t}h which corresponds to the electric field of about 2 kV/cm the current increased abruptly by a few orders of magnitude. The value of V_{t}h increased with the temperature. It is proposed that the observed shape of the I-V curve is caused by the filling of the EL2 level with injected electrons heated by the electric field.
2
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Conductivity Effects in Bi₂TeO₅ Single Crystals

100%
Agarkov K., Sadovskaya L.
Acta Physica Polonica A
|
2018
|
vol. 133
|
issue 4
940-942
EN
The current-voltage characteristics (I-V) of non-stoichiometric bismuth tellurite crystals were studied in a range of temperatures from 150°C to 350°C and fields up to 2.5 kV/cm with asymmetric contacts (In-Ga eutectic and Na₂SiO₃). The I-V curves and observed monopolar injection are described by the approximation of space charge limited currents. In the composition of 47% Bi₂O₃-53% TeO₂ electronic conduction is prevailed. In the composition 43% Bi₂O₃-57% TeO₂ the conductivity is contributed by electrons and holes. The spectrum of local states in the band gap of the studied crystals is quasicontinuous, which cannot be described by models of a discrete or exponential distribution.
3
Content available remote

Monte Carlo Estimation of the Efficiency of the Three Center Auger Effect

100%
Żakrzewski A.
Acta Physica Polonica A
|
1992
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vol. 82
|
issue 5
899-901
EN
In this communication the effect of impurity quenching of the photoluminescence of ZnS crystals is discussed. An appropriate mechanism of non- radiative recombination is proposed and its efficiency is estimated.
4
Content available remote

On the Pinning of the Fermi Level by Germanium A_{1}^{0/+} Deep Donor State in GaAs Codoped with Ge and Te

100%
Słupiński T., Nowak G., Przybytek J., Stępniewski R.
Acta Physica Polonica A
|
1993
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vol. 84
|
issue 4
807-811
EN
We present the possibility of GaAs:Ge,Te crystals growth from the melt (liquid encapsulated Czochralski method) with partially occupied, at ambient pressure, the A_{1} localized electronic state of Ge_{Ga} impurity. In as-grown crystals the amphotericity of Ge and creation of defects (deep acceptor complexes, precipitates etc.) during cooling after growth limit the free electron concentration below the value necessary to populate the A_{1}^{0/+} level. Special annealing of the samples, which enlarges the free electron concentration, was used. The occupation of A_{1}^{0/+} level, at ambient pressure, was observed by pressure dependent Hall effect measurements.
5
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Optical Nonlinearities in Bulk GaAs Determined by EL2 Defect

100%
Sudzius M., Bastiene L., Svitojus S., Jarasiunas K.
Acta Physica Polonica A
|
1996
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vol. 90
|
issue 5
939-942
EN
Time-resolved studies of light diffraction on free carrier phase gratings and light absorption in subnanosecond time domain were carried out in two distinct areas of semi-insulating GaAs with high and low growth-defect density. Numerical analysis was performed in order to reveal the role of EL2 defect in carrier generation and transport. The possibility of transient grating technique to study various defect-governed carrier relaxation processes were demonstrated experimentally.
6
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On the Tunneling Among Shallow and Deep Centers in ZnS

63%
Zakrzewski A., Sienkiewicz A.
Acta Physica Polonica A
|
1991
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vol. 79
|
issue 2-3
251-254
EN
Results of the photo-ESR studies of recharging processes due to tunneling in ZnS:Cu crystals are presented. It was found that the tunneling among shallow and deep centers seems to be a second order effect in the overall photoluminescence quenching in ZnS by transition metal impurities.
7
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Influence of Defects Introduced by Irradiation with 4-9 MeV Helium Ions on Impedance of Silicon Diodes

63%
Poklonski N., Gorbachuk N., Nha V., Shpakovski S., Filipenya V., Skuratov V., Kołtunowicz T., Kukharchyk N., Becker H., Wieck A.
Acta Physica Polonica A
|
2015
|
vol. 128
|
issue 5
891-893
EN
Silicon diodes irradiated with helium ions with energies of 4.1, 6.8 and 8.9 MeV are studied. It is shown that the mechanism determining the behaviour of frequency dependence of complex electric module and correspondingly the behavior of impedance of diodes irradiated with helium ions in the frequency region 3-200 kHz is a recharging of vacancy complexes localized in the space charge region.
8
Content available remote

Transient Photo-Induced Current Measurements in High Resistivity ZnSe Crystals

63%
Bała W., Firszt F., Dul D., Turlo Z., Borkowski J.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 2-3
295-298
EN
Using technique of computerized signal-averaging of photocurrent transient, we have studied the details of deep level states in high resistivity ZnSe crystals. The time resolved spectra of photocurrent and four-gate PICT spectra are presented.
9
Content available remote

Photoconductivity in GaAlAs:Si Proves Negative U of DX Centers

63%
Wilamowski Z., Jantsch W., Ostermayer G.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 2
283-286
EN
The analysis of the temperature dependence of the photoconductivity, amplitude in doped GaAlAs, provides a simple and convincing proof of the negative sign of the Hubbard correlation energy U, strictly speaking of the two-electron nature of the thermal emission process from DX centers. The proof is based on a comparison of the emission activation energy measured per emission event (DLTS) with that measured per electron.
10
Publication available in full text mode
Content available

Slowup of Bimolecular Recombination in Organic Polymer Solar Cells

63%
Nunzi J., Juška G., Jean F., Arlauskas K.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
377-380
EN
For the retrieval of best polymers for effective organic solar cells as testing parameter we have used the coefficient of bimolecular recombination (B). The B measurement demonstrated that in pure MEH-PPV layers its value is close to the value of Langevin recombination coefficient (B_L), while in case of perylene/MEH-PPV junction layers the ratio B/B_L≅0.013, and in blends of MEH-PPV with PCBM B/B_L<:0.01.
11
Content available remote

Photo-EPR Investigations of Thermal Donors in Silicon

63%
Bagraev N., Bekman H., Gregorkiewicz T., Ammerlaan C.
Acta Physica Polonica A
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1991
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vol. 79
|
issue 2-3
397-400
EN
Two thermal donor related EPR centers Si-NL8 and Si-NL10 were studied by the photo-EPR technique. The spectral dependence of the intensity of the EPR signals was determined for the region from 0.6 to 1.4 eV in several samples with different Fermi level position. The quenching of the Si-NL8 signal with the coinciding enhancement of the Si-NL10 signal has been observed with possible indication of some metastable behavior of the NL8 center. For the heavily aluminum doped material strong generation of photocurrent upon band gap illumination has been observed. The results of the study provide further evidence for mutal correlation of both thermal donor related EPR centers since the observed spectral dependences could be understood by relating both NL8 and NL10 spectra to different paramagnetic states of basically the same center.
12
Content available remote

Quasiparticles in Calcium Doped Yttrium-Iron Garnets

63%
Lehmann-Szweykowska A., Wojciechowski R. J., Gehring G. A., Tobijaszewski I.
Acta Physica Polonica A
|
1997
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vol. 91
|
issue 2
423-426
EN
In yttrium-iron garnets an electrical charge is carried by quasiparticles based on compensating holes which move either at oxygen or iron ions of the tetragonal sublattice. The quasiparticles can also get localized because of their coupling to optical phonons on the iron sites. A multi-band model of holes coupled to phonons is applied to find additional energy levels in the gap between the lower of the narrow 3d bands and the wide 2p band, whose occurrence plays a crucial role in a conductivity mechanism. The density of states is considerably modified by the interaction between the holes and local distortion of the lattice.
13
Content available remote

DX Puzzle: Where Are We Now?

63%
Wilamowski Z., Suski T., Jantsch W.
Acta Physica Polonica A
|
1992
|
vol. 82
|
issue 4
561-571
EN
A brief review of the experimental data on the metastable DX-centers in AlGaAs is presented. The experimental proofs of the two-electron nature and of the intermediate, one-electron state of the DX-centers are discussed. We collect the available experimental data on the ground state, electron-emission and capture energies and we discuss the nature of the lattice barrier. The effect of splitting of these energies in AlGaAs alloys and the consequences of the splitting on the capture and emission kinetics are analyzed. The different character of the barrier and of the alloy splitting for donors of the IV and VI group is underlined. The necessity to consider the interdonor Coulomb interaction when discussing the experimental data is also pointed out.
14
Content available remote

SiO_{2} Layer Charge State Variation in Fowler-Nordheim Tunneling Regime

63%
Strzałkowski I., Kowalski M.
Acta Physica Polonica A
|
1997
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vol. 92
|
issue 3
585-590
EN
The charge build-up and its changes in the amorphous SiO_{2} layer incorporated into a Si MOSFET as a gate oxide due to Fowler-Nordheim tunneling electron injection were investigated. Electron and hole trapping/detrapping by native and generated trap centres were studied by monitoring the charge state of the SiO_{2} traps by means of a drain-source current versus gate-source voltage technique. New interesting effects were observed and their possible mechanisms are presented.
15
Content available remote

Effects of Fluences of Irradiation with 107 MeV Krypton Ions on the Recovery Charge of Silicon p^{+}n-Diodes

63%
Poklonski N., Gorbachuk N., Tarasik M., Shpakovski S., Filipenia V., Skuratov V., Wieck A., Kołtunowicz T.
Acta Physica Polonica A
|
2011
|
vol. 120
|
issue 1
111-114
EN
The diodes manufactured on the wafers of single-crystalline silicon uniformly doped with phosphorus are studied. The wafer resistivity was 90 Ω cm. Krypton ions are implanted to the side of the p^{+}-region of diodes (energy 107 MeV, fluence Φp from 5 × 10^7 to 4 × 10^9 cm^{-2}). It is shown that recovery charge Q_{rr} is inversely proportional to the square root of the irradiation fluence value Φp. When the fluence increases, the part of the recovery charge Q_{rrA}, due to the high reverse conductance phase, decreases faster than the value Q_{rr}.
16
Content available remote

Luminescence Decay Kinetics in GaN Studied by Frequency Domain Measurements

63%
Mickevičius J., Vitta P., Tamulaitis G., Žukauskas A., Shur M., Zhang J., Yang J., Gaska R.
Acta Physica Polonica A
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2008
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vol. 113
|
issue 3
833-837
EN
Carrier dynamics in high-quality GaN epilayer was investigated at two extreme excitation levels. Carrier lifetime under high excitation conditions was estimated by using light-induced transient grating technique. Measurements at extremely low excitation power density were performed by using frequency-domain fluorescence lifetime technique. The study was performed in a wide temperature range from 8 to 300 K. The results revealed the influence of donor-acceptor pair recombination and carrier trapping processes.
17
Content available remote

Investigation of Optical Nonlinearities and Carrier Dynamics in In-Rich InGaN Alloys

63%
Nargelas S., Malinauskas T., Jarasiunas K., Dimakis E., Georgakilas A.
Acta Physica Polonica A
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2008
|
vol. 113
|
issue 3
839-843
EN
We present experimental studies of nonequilibrium carrier dynamics in InGaN alloys with 70-90% content of In by using picosecond transient grating technique. The observed faster recombination rate in alloys with higher Ga content and formation of a thermal grating via a lattice heating, being more pronounced for layers with larger band gap, indicated that the main reason of the heating is not the excess energy of photons, but the defect density which increases with Ga content. A gradual decrease in carrier lifetime with excitation or with increasing temperature in 50-300 K range point out the role of potential barriers in carrier recombination.
18
Content available remote

Current-Voltage Characteristic Features of Diodes Irradiated with 170~MeV Xenon Ions

63%
Poklonski N., Gorbachuk N., Nha V., Tarasik M., Shpakovski S., Filipenia V., Skuratov V., Wieck A., Kołtunowicz T.
Acta Physica Polonica A
|
2013
|
vol. 123
|
issue 5
926-928
EN
Diodes manufactured on the wafers of single-crystalline silicon uniformly doped with phosphorus are studied. The wafer resistivity was 90 Ω cm. Xenon ions were implanted into the diodes from the side of the p^{+}-region (implantation energy 170 MeV, fluence Φp from 5 × 10^7 to 10^9 cm^{-2}). It is shown that the formation of a continuous irradiation damaged layer with the thickness of the order of magnitude of the average projective range creates prerequisites for the negative differential resistance in the current-voltage characteristics of the irradiated diodes.
19
Content available remote

On Oscillating Carrier Dynamics in Highly Excited InP:Fe Crystals

63%
Subačius L., Kadys A., Jarašiūnas K., Kamiński P.
Acta Physica Polonica A
|
2008
|
vol. 113
|
issue 3
855-858
EN
The numerical analysis and experimental data on time-resolved four-wave mixing confirmed a novel origin of oscillations in subnanosecond carrier dynamics in highly excited InP:Fe crystals. The effect was attributed to simultaneous presence of electron and hole gratings, which drift in the space charge field and contribute constructively or destructively to refractive index modulation in time domain.
20
Content available remote

Trapping Center Parameters in N-Implanted Tl_2Ga_2S_3Se Single Crystals by Thermally Stimulated Currents Measurements

51%
Yildirim T., Gasanly N., Turan R.
Acta Physica Polonica A
|
2013
|
vol. 123
|
issue 4
766-769
EN
As-grown Tl_2Ga_2S_3Se crystals have been doped by ion implantation technique. The samples were bombarded at room temperature in the direction perpendicular to the layer by N ion beam of about 120 keV having dose of 1 × 10^{16} ions/cm^2. The effect of N implantation with annealing at 300C was studied by using thermally stimulated current measurements. The investigations were performed in temperatures ranging from 10 to 290 K. The experimental evidence was found for presence of one deep hole trapping center with activation energy of 392 meV. The capture cross-section was calculated as 3.9 × 10^{-20} cm^2. Also the concentration of the traps was estimated to be 8.0 × 10^{11} cm^{-3}.
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