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1
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Pb_{1-x}Mn_xTe Crystals as a New Thermoelectric Material

100%
Osinniy V., Jędrzejczak A., Domuchowski W., Dybko K., Witkowska B., Story T.
Acta Physica Polonica A
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2005
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vol. 108
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issue 5
809-816
EN
We studied experimentally thermoelectric properties of p-type bulk crystals of Pb_{1-x}Mn_xTe and Pb_{1-x-y}Ag_yMn_xTe (0≤ x≤ 0.083 and y≤0.017) at room and liquid nitrogen temperatures. Model calculations of the thermoelectric figure of merit parameter (Z) involved the analysis of carrier concentration, carrier mobility, density of states as well as electronic and lattice contributions to the thermal conductivity of PbMnTe. In the analysis we took into account the main effect of Mn concentration on the band structure parameters of PbMnTe, i.e. the increase of the energy gap. The analysis of electrical, thermoelectric, and thermal properties of Pb_{1-x}Mn_xTe crystals showed that, at room temperature, the maximum values of the parameter Z occur in crystals with Mn content 0.05≤ x≤0.07 and are comparable with a maximal value of Z observed in PbTe. At T=400 K the increase in the parameter Z by 10% is expected in Pb_{1-x}Mn_xTe crystal (as compared to PbTe) for a very high concentration of holes of about p=5×10^{19} cm^{-3}. The experimental data correctly reproduce the theoretical Z(p) dependence.
2
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Electric Polarization of Onsager Fluids. II. Birefringence. 1. Kerr Constants of Pure Substances

100%
Prezhdo V., Tarasova G., Prezhdo O., Tyurin S., Akulova O., Kurskaya T.
Acta Physica Polonica A
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1994
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vol. 85
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issue 5
797-804
EN
The Kerr constants of pure liquid organic compounds, which exhibit weak intermolecular interactions and possess widely varying electric, optical and polarizational molecular parameters, were computed from the data on dielectrometry and electric birefringence. Good agreement of the calculated and observed values was reached as the result of the introduction of the local field model, which develops the concepts of reactive field and local electric induction of a polarized fluid, into the orientational theory of the Kerr effect.
3
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Substrate-Induced Strain in Epitaxial Lead Chalcogenides by Galvanomagnetic Effect Rotational Dependence

100%
Berchenko N. N., Dobriansky O. A., Korovin A. V., Nikiforov A. Y., Yakovyna V. S., Zogg H.
Acta Physica Polonica A
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1997
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vol. 92
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issue 4
715-718
EN
On the example of the PbTe and Pb_{0.77}Sn_{0.23}Te on BaF_{2} the possibility of using the weak magnetic field resistance technique for the evaluation of mismatch-thermally induced strains in semiconductors with multivalley band structure is discussed.
4
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Trapping Center Parameters in TlInS_2 Layered Crystals by Thermally Stimulated Current Measurements

100%
Yuksek N., Gasanly N., Ozkan H., Karci O.
Acta Physica Polonica A
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2004
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vol. 106
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issue 1
95-103
EN
Thermally stimulated current measure ments are carried out on TlInS_2 layered single crystal with the current flowing perpendicular to the c-axis in the temperature range of 10 to 90 K. The results are analyzed according to various methods, such as curve fitting, heating rate, and initial rise methods, which seem to be in good agreement with each other. Experimental evidence is found for one trapping center in TlInS_2 crystal in the low-temperature region.
5
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Ballistic Transport Phenomena in Nanostructures of Paraelectric Lead Telluride

80%
Grabecki G.
Acta Physica Polonica A
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2007
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vol. 112
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issue 2
127-139
EN
This is a review of our recent developments in the physics of lead telluride nanostructures. PbTe is a IV-VI narrow gap paraelectric semiconductor, characterized by the huge static dielectric constant ε >1000 at helium temperatures. We nanostructurized this material by means of e-beam lithography and wet chemical etching of modulation doped PbTe/Pb_{1-x}Eu_xTe quantum wells. Magnetoresistance measurements performed on the nano-structures revealed a number of magnetosize effects, confirming a ballistic motion of the carriers. The most important observation is that the conductance of narrow constrictions shows a precise zero-field quantization in 2e^2/h units, despite a significant amount of charged defects in the vicinity of the conducting channel. This unusual result is a consequence of a strong suppression of the Coulomb potential fluctuations in PbTe, an effect confirmed by numerical simulations. Furthermore, the orbital degeneracy of electron waveguide modes can be controlled by the width of PbTe/Pb_{1-x}Eu_xTe quantum wells, so that unusual sequences of plateau conductance can be observed. Finally, conductance measurements in a nonlinear regime allowed for an estimation of the energy spacing between the one-dimensional subbands.
6
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Electrical and Magnetic Studies of the Cd_{x}Cr_{y}V_{z}Se_{4} Spinels

80%
Groń T., Duda H., Malicka E., Zawisza B., Krok-Kowalski J., Pacyna A.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
969-970
EN
The electrical and magnetic investigations carried out on the polycrystalline spinels with the general chemical formula Cd_{x}Cr_{y}V_{z}Se_{4} (where z = 0.06, 0.12, 0.24, and 0.31) revealed semiconducting and ferromagnetic properties with a Curie temperature of 127.5 K. A step-like structure of the electrical conductivity, σ(T), was observed for the polycrystal containing 6% V ions in the octahedral sites while the remaining samples showed a typical Arrhenius behaviour of σ(T). These effects are interpreted in terms of ferromagnetic spin clusters which finally dissolve on going towards the paramagnetic limit including non-stoichiometry.
7
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Application of the Electro-Optical Kerr Effect in Physical-Chemical Analysis of Binary Systems

80%
Prezhdo O., Tyurin S., Pisarczyk M., Odziemek A., Prezhdo V.
Acta Physica Polonica A
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2002
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vol. 101
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issue 4
477-494
EN
Applications of the electro-optical Kerr effect in physical-chemical analysis of binary mixtures are reviewed. Improvements in the experimental techniques, in particular, development of the pulsed and alternating electric field based approaches, have led to significant advances in this area. However, problems associated with the description of the internal field of liquids remain and hamper broader applications of the techniques. It is shown that a further progress in the electro-optical Kerr effect characterization of chemical systems relies on the development of a more general theory of optical properties of condensed phase chemical mixtures that can account for nonlinear effects, such as hyperpolarizability, dispersion and specific conditions of the Kerr constant measurements.
8
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Ferromagnetic Order in Single-Crystalline (Cd_{x}Al_{y})[Cr_2]Se_{z} Semiconductors

80%
Duda H., Rduch P., Malicka E., Groń T., Kusz J.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
702-704
EN
Measurements of the magnetic properties, the electrical conductivity and the Seebeck effect were performed on single crystals (Cd_{x}Al_{y})[Cr_2]Se_{z} between 77 and 300 K. All samples have a ferromagnetic order with the Curie temperature of 130 K and the paramagnetic Curie-Weiss temperature of 155 K. Both these temperatures do not depend significantly on the Al substitution. The electrical conductivity of single crystals CdCr_2Se_4 doped with Al was p-type and showed the change of log σ versus 1/T slope above 150 K. This fact is interpreted as being due to the onset of impurity conduction and structural defects.
9
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Electric Polarization of Onsager Fluids. II. Birefringence. 2. Molar Kerr Constants of Binary Solutions

80%
Prezhdo V. V., Tarasova G. V., Prezhdo O. V., Tyurin S. A., Akulova O. N., Kurskaya T. N.
Acta Physica Polonica A
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1994
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vol. 86
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issue 3
327-332
EN
On the ground of dielectrometry and electric birefringence data we calculated molar Kerr constants of substances dissolved in organic media of diverse polarity and polarizability under the conditions of infinite dilution. Minimal errors of the calculated constants, in relation to their gaseous phase values, were achieved as a result of the introduction of the local field model, which evolves the concepts of reactive field and local electric induction of a polarized fluid, into the orientational theory of Kerr effect.
10
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Mictomagnetic Order in Cd_{0.87}Cr_{1.93}V_{0.06}Se_4 Semiconductor

80%
Groń T., Malicka E., Zawisza B., Duda H., Krok-Kowalski J., Pacyna A.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
714-716
EN
The complex ac dynamic magnetic susceptibility was used to study the mictomagnetic-like behavior in polycrystalline Cd_{0.87}Cr_{1.93}V_{0.06}Se_4 spinel. The temperature dependences of the zero field in-phase (real part) and out-of-phase (imaginary part) components of fundamental susceptibility measured at the oscillating field H_{ac} = 0.5 Oe and at the constant frequency of 125 Hz are characteristic for the mictomagnetic order. These results well correlate with the anomalies in the second and third harmonics of the ac susceptibility indicating the cluster glass.
11
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Hopkinson-Like Effect in Single-Crystalline CdCr_2Se_4 and Cd[Cr_{1.89}Ti_{0.08}]Se_4

80%
Malicka E., Groń T., Pacyna A., Duda H., Krok-Kowalski J.
Acta Physica Polonica A
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2012
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vol. 121
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issue 3
690-693
EN
The static (dc) and dynamic (ac) magnetic measurements of CdCr_2Se_4 and Cd[Cr_{1.89}Ti_{0.08}]Se_4 showed their ferromagnetic properties with a Curie temperature T_{C} ≈ 130 K and revealed on the real component of ac susceptibility curve, the peaks near T_{C} at 200 Oe, 450 Oe and 1 kOe, characteristic for the Hopkinson ones. The meaningful reduction of saturation moment to 4.73 μ_{B}/f.u. for Cd[Cr_{1.89}Ti_{0.08}]Se_4 suggests the diamagnetic configuration of Ti ions, which dilutes the ferromagnetic sublattice of Cr ones and causes reducing of the energy losses visible on the imaginary components of ac susceptibility curve. Close for zero values of higher susceptibility harmonics above T_{C} are pointing out to the lack of the spin fluctuations in the paramagnetic state.
12
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Pressure Study of Charged Donor Ordering in HgSe Doped with Iron and Gallium

80%
Skierbiszewski C., Suski T., Kossut J., Wilamowski Z., Dobrowolski W., Witkowska B.
Acta Physica Polonica A
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1991
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vol. 80
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issue 3
401-404
EN
Transport experiments (Hall effect and conductivity) under hydrostatic pressure up to 1 GPa at liquid helium temperatures on HgSe: Fe, Ga (N_{Fe} = 2 x 10^{19} cm^{-3}; 0 ≤ N_{Ga} ≤ 10^{19} cm^{-3}) were performed. The results show that the gallium co-doping of HgSe:Fe decreases the degree of spatial correlations between charged impurities. Under the hydrostatic pressure, used as a tool for changing the ratio of the charged to neutral impurities, this effect is even more pronounced. A qualitative agreement between the calculation within the short-range correlation model and our experimental data is achieved.
13
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Electron Scattering and the Band Structure of Mixed Crystals Hg_{1-x}Fe_{x}Se

80%
Skierbiszewski C., Wilamowski Z., Suski T., Kossut J., Witkowska B.
Acta Physica Polonica A
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1992
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vol. 82
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issue 5
809-812
EN
In this paper the dependence of the band structure and the electron scattering mechanisms on the molar fraction x are studied in Hg_{1-x}Fe_{x}Se. The crossover from the zero-gap band to the open band-gap configuration at x ≈ 0.08 is predicted. We explain the drop of the electron mobility for x > 0.002 by the alloy scattering mechanism.
14
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Thermally Stimulated Current Study of Shallow Traps in As-Grown TlInSe_2 Chain Crystals

80%
Gasanly N., Yildirim T.
Acta Physica Polonica A
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2011
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vol. 119
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issue 3
437-441
EN
Thermally stimulated current measurements were carried out on as-grown TlInSe_2 single crystals. The investigations were performed in temperatures ranging from 10 to 260 K with heating rate of 0.3 K s^{-1}. The analysis of the data revealed the hole traps levels located at 6 and 57 meV. The activation energies of the traps have been determined using various methods of analysis, and they agree with each other. The concentration (2.8 × 10^{13} and 3.4 × 10^{12} cm^{-3}) and capture cross section (4.1 × 10^{-28} and 2.9 × 10^{-26} cm^2) of the traps were estimated for peaks A and B, respectively. It was concluded that in these centers retrapping was negligible, as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping.
15
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Electrical and Magnetic Characterization οf ZnCr_{2-x}V_{x}Se_{4} Spinel Semiconductors

80%
Duda H., Malicka E., Groń T., Pacyna A., Kusz J.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
962-963
EN
Single crystals of ZnCr_{2}Se_{4} spinel doped with vanadium were prepared by chemical vapour transport. The chemical compositions of three crystals have been determined by X-ray diffraction. The structure refinement using the SHELXL-93 program system determine the cation distribution in the system as ZnCr_{2-x}V_{x}Se_{4}. For x values equal to 0.03, 0.1 and 0.13 the observed symmetry was cubic, space group Fd3m. Based on the structural data, influence of the V ions on the magnetic and electrical properties has been analyzed.
16
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Electric Polarization of Onsager Fluids. II. Birefringence. 3. Role of Universal Pairwise Interactions

80%
Prezhdo V., Tarasova G., Prezhdo O., Tyurin S., Akulova O., Ivanov N.
Acta Physica Polonica A
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1996
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vol. 89
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issue 1
47-59
EN
A comparative analysis of several methods of interpretation of solvent influence on molar Kerr constants of solutes was done. The analysis was based on experimentally determined electro-optical and dielectric properties of binary solutions of organic substances with various polarities, polarizabilities and optical anisotropies. It was found that the role of universal van-der-Waals interactions treated via London-Debye-Keesom potentials was best accounted for by a modified orientational theory of Kerr effect that developed the ansatz of reactive field and local dielectric permittivity. An extrapolation method of determination of gas phase molar Kerr constants of solutes was deduced from the theory.
17
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Deep Traps Distribution in TlInS_2 Layered Crystals

80%
Isik M., Gasanly N., Ozkan H.
Acta Physica Polonica A
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2009
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vol. 115
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issue 3
732-737
EN
The trap centers and distributions in TlInS_2 were studied in the temperature range of 100-300 K by using thermally stimulated currents technique. Experimental evidence was found for the presence of three trapping centers with activation energies 400, 570, and 650 meV. Their capture cross-sections were determined as 6.3 × 10^{-16}, 2.7× 10^{-12}, and 1.8× 10^{-11} cm^{2}, respectively. It was concluded that in these centers retrapping is negligible as confirmed by the good agreement between the experimental results and the theoretical predictions of the model that assumes slow retrapping. An exponential distribution of hole traps was revealed from the analysis of the thermally stimulated current data obtained at different light excitation temperatures. This experimental technique provided a value of 800 meV/decade for the trap distribution.
18
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Effect of Trap Levels and Defect Inhomogeneities on Carrier Transport in SiC Crystals and Radiation Detectors

80%
Kažukauskas V., Kalendra V., Vaitkus J.
Acta Physica Polonica A
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2005
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vol. 107
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issue 2
333-339
EN
We present investigation of carrier transport and trapping in 4H-SiC single crystals and high-energy radiation detectors. SiC detectors were produced from bulk vanadium-compensated semi-insulating single crystal 4H-SiC and provided with nickel ohmic and titanium Schottky contacts. The prevailing defect levels were revealed by means of thermally stimulated current and thermally stimulated depolarization methods and their advanced modification - multiple heating technique. From I-V measurements a Schottky barrier height of≈1.9 eV was found. In 4H-SiC:Va the following thermal activation values were deduced: 0.18-0.19 eV, 0.20-0.22 eV, 0.3-0.32 eV, 0.33 -0.41 eV, and 0.63 eV. The maximum with activation energy of 0.33-0.41 eV appears below 125 K and most probably is caused by thermal carrier generation from defect levels. In contrast, the first three maxima with lowest activation energies, which appear at higher temperatures, are likely associated with material inhomogeneities causing potential fluctuations of the band gap. The existence of different polarization sources in different temperature ranges is also demonstrated by thermally stimulated depolarization.
19
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Peculiarities of Electron Transport in PbTe:Cr due to Presence of Resonant Impurity State

80%
Grodzicka E., Dobrowolski W., Kossut J., Story T., Witkowska B.
Acta Physica Polonica A
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1993
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vol. 84
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issue 3
599-603
EN
The results of transport investigation of Pb_{1-x}Cr_{x}Te (x ≤ 0.009) in temperature range 3.5-300 K are presented. The obtained electron concentration and electron mobility vs. temperature and Cr concentration data are interpreted and discussed within the model assuming that Cr in PbTe forms a donor state resonant with the conduction band.
20
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Trapping Center Parameters in N-Implanted Tl_2Ga_2S_3Se Single Crystals by Thermally Stimulated Currents Measurements

80%
Yildirim T., Gasanly N., Turan R.
Acta Physica Polonica A
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2013
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vol. 123
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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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