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  1. 30 Acta Physica Polonica A

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  1. 5 Dobaczewski L.

  2. 4 Grabecki G.

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  4. 3 Dietl T.

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1
Content available remote

Electrical Properties of Anisotype ZnO/ZnSe Heterojunctions

100%
Makhniy V., Khusnutdinov S., Gorley V.
Acta Physica Polonica A
|
2009
|
vol. 116
|
issue 5
859-861
EN
The p-ZnO/n-ZnSe heterojunction was prepared by the photothermal oxidation of ZnSe substrate. Current- voltage characteristics are measured and discussed. The potential barrier height is equal to 3 eV at 300 K and its anomalous temperature coefficient reported here is due to the high defects concentration ( ≈ 10^{14} cm^{-2}) on the interface. It is established that forward current in p-n junction is limited by the recombination processes in the space charge region, carriers tunneling and above the barrier emission. The reverse current is determined by tunneling processes at low bias and avalanche effect at high bias.
2
Content available remote

Quasi Fermi Levels in Semiconductor Photovoltaic Heterojunction

100%
Orlowski B., Pieniazek A., Goscinski K., Kopalko K.
|
EN
The photovoltaic heterojunction elements are build of two different semiconductors of n and p type. Under cell illumination the same density of n and p carriers are created in each generation point but it leads to the remarkably higher increase of relative concentration for minority than for majority carriers. It is causing bigger energy change of the quasi Fermi level of minority than of majority carriers. The minority carriers decide of the value of generated photovoltage while the majority carriers contribution to it, in most cases can be neglected. Measured change of the generated open circuit photovoltage versus illumination light intensity allows to estimate corresponding to it increase of the minority carrier concentration. These allows as well to scan the part of the forbidden gap region by the minority carriers quasi Fermi level and in a case of impurity or defect levels located in forbidden gap it can influence on the continuous dependence of generated photovoltage versus light intensity e.g. for pinning of the Fermi level. To create efficient photovoltaic heterojunction it will need to study electronic properties of the used impurities and their proper distribution in the region of junction.
3
Content available remote

Conductance Fluctuations in Microstructures of HgCdMnTe Bicrystals

100%
Grabecki G., Lenard A., Plesiewicz W., Jaroszyński J., Cieplak M., Skośkiewicz T., Dietl T., Kamińska E., Piotrowska A., Bulka B.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 2
307-310
EN
Microscopic four-contact probes to semimagnetic HgCdMnTe grain-boundary inversion layers have been photolithographically patterned. Magnetoresistance measurements performed on these samples revealed aperiodic conductance fluctuations of the magnitude of the order of e^{2}/h. Quantitative analysis of both fluctuation amplitude and their mean period indicate that we have approached the mesoscopic regime in our system. This opens new possibilities in studies of spin-subsystem dynamics in semimagnetic semiconductors.
4
Content available remote

Optical Studies of HgCdMnTe Bicrystals

63%
Grabecki G., Wróbel J., Karczewski G.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 2-3
221-223
EN
We report preliminary results of optical measurements performed on Hg_{1-x-k}Cd_{x}Mn_{k}Te grain boundaries. Photovoltaic spectra and I-V characteristics under illumination exhibit metastable behavior, confirming our previous conclusions based on transport measurements under high hydrostatic pressure.
5
Content available remote

Deformation Potentials in IV-VI Quantum Wells

63%
Litvinov V., Dugaev V., Oszwałdowski M.
Acta Physica Polonica A
|
1995
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vol. 87
|
issue 2
345-348
EN
Theoretical studies of the deformation potentials in quantum wells and superlattices are presented. It is shown that a difference exists between the bulk deformation potentials and deformation potentials in the low dimen­sional structures made of narrow-gap semiconductors.
6
Content available remote

Interface Energy Spectrum of Real PbTe/SnTe Heterojunction

63%
Litvinov V., Oszwałdowski M.
Acta Physica Polonica A
|
1992
|
vol. 82
|
issue 5
805-808
EN
The interface energy spectrum in real band-inverted PbTe/SnTe heterojunctions formed both in the (111) and (001) planes is calculated. It is shown that even if the valence band of SnTe lies above the conduction band minimum of PbTe, the interface, midgap states may still exist due to the strain effect on the band gaps.
7
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Transmission Coefficient for a Double-Barrier Quantum Well Structure

63%
Kaczmarek E., Szkiełko W.
Acta Physica Polonica A
|
1991
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vol. 80
|
issue 3
441-444
EN
In this paper the transmission coefficient for a double-barrier quantum well (DBQW) structure as a function of applied voltage is calculated, for the first time, using WKB approximation: This approach allows to discuss a dependence of several quantities characteristic of the system (e.g. the value of the coefficient, resonance voltage, charge stored in the well) on the barrier and the well parameters.
8
Content available remote

Temperature Dependence of Properties of Heterojunctions of Some TCNQ Salts in Polymer Matrices with p- or n-Doped Silicon

63%
Jeszka J. K., Tracz A., Boiteux G., Seytre G., Kryszewski M.
Acta Physica Polonica A
|
1995
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vol. 88
|
issue 3
533-541
EN
The temperature dependence of the electrical properties of heterojunctions with silicon formed by conductive organic polymer composites with networks of two complex tetracyanoquinodimethane salts (of N-n-butyl-isoquinolinium and of diethyl methyl sulphonium cations) were studied. We show that it is possible to prepare junctions with quite good rectifying properties, comparable to those obtained using other organic semiconductors. The observed forward-bias current-voltage characteristics can be satisfactorily fitted using the modified Schottky equation. Reverse bias and C-V characteristics show that the transport mechanism, especially in the case of p-Si junctions is more complicated and probably tunnelling between localized levels plays an important role.
9
Content available remote

Iron-Boron Pair in Silicon: Old Problem Anew

51%
Dobaczewski L., Surma M.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 4
613-622
EN
For the iron-boron pair in the p-type silicon two different configurations of the defect are observed: stable and metastable. The reported metastable configuration is the first step in a dissociation process of the stable, i.e. of trigonal symmetry, configuration of the pair. Rate equations for the two-step iron-boron pair dissociation allowed us to evaluate the dissociation rates for both configurations of the pair. The driving force for the creation and, then, dissociation of the metastable pair is the minority carrier injection followed by the electron-hole recombination process in the space charge region. A use of the high-resolution Laplace-transform deep level transient spectroscopy allowed us to demonstrate for both of the configurations the influence of the magnetic field on the hole emission.
10
Content available remote

Conductance of a Quantum Wire with Finite Length

51%
Suhrke M., Wilke S., Keiper R.
Acta Physica Polonica A
|
1991
|
vol. 79
|
issue 2-3
217-220
EN
The conductance of a ballistic quantum wire between two reservoirs exhibits steps of height 2e^{2}/h, if the occupation of transverse subbands is changed. We investigate conditions for observation of these steps starting from Kubo-Greenwood formula. We show how the conductance steps are influenced by the properties of the external regions as well as by the nature of the connection between these regions and the wire. Furthermore we incorporate residual scattering in long wires.
11
Content available remote

Photoresponse of Porous Silicon Structures to Infrared Radiation

51%
Samuolienė N., Širmulis E., Stupakova J., Gradauskas J., Zagadskij V., Šatkovskis E.
Acta Physica Polonica A
|
2011
|
vol. 119
|
issue 2
137-139
EN
Photoresponse of silicon samples containing porous structures have been studied under the action of CO_2 laser radiation. The signal shape and its behavior under the applied bias voltage revealed the existence of two heterojunctions on the border of porous-crystalline silicon and on the border between the porous layers of different porosity. The photosignal is recognized to be composed of hot hole photoemfs induced across the heterojunctions.
12
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Electron Liquids in Coupled Quantum Wells

51%
Świerkowski L., Szymański J., Neilson D.
Acta Physica Polonica A
|
1993
|
vol. 84
|
issue 3
445-457
EN
A system comprising of two adjacent layers of conduction electrons or alternatively a layer of electrons and a layer of holes can exhibit novel instabilities in the liquid phase towards inhomogeneous ground states. The carriers in the two layers can couple to each other through the Coulomb interaction but they are not permitted to tunnel so that the charges in one layer act as a polarisable background for the other layer. The presence of a second layer encourages the formation of novel ground states with inhomogeneous density distributions. We find theoretical evidence for the existence of charge density wave ground states and also a coupled Wigner crystal. These exist at much higher densities than the Wigner crystallisation density for the single layer case. The existence of these inhomogeneous ground states leads to significant modifications of the low lying excitation spectrum in the uniform liquid phase. Near the transitions to both the charge density wave and the coupled Wigner crystal phases we find evidence of the development in the liquid phase of new soft mode excitations of finite wave number q that are precursors of the inhomogeneous ground states. Near the transition to the coupled Wigner crystal we observe a strong tendency of the single particle excitation spectrum for the liquid phase to renormalise into a single line that has a dispersion closely resembling the phonon dispersion curve for the solid.
13
Content available remote

Investigation of Localized Electric Field in the Type-II InAs/GaAsSb/GaAs Structure

51%
Lee S., Kim J., Yoon S., Kim Y., Lee S., Honsberg C.
Acta Physica Polonica A
|
2016
|
vol. 130
|
issue 5
1213-1216
EN
The effect of localized electric field (F) was investigated in the type-II InAs/GaAsSb/GaAs structures. To compare type-I to type-II, two types of samples with different Sb contents was grown by molecular beam epitaxy, whose Sb contents are 3% (type-I) and 16% (type-II), respectively. In the both samples, we performed excitation power dependent-photoreflectance at 10 K and the result showed that the period of the Franz-Keldysh oscillation, revealed above the band gap (E_{g}) of GaAs, was broadened in the only type-II system, which means that F was also increased because it is proportional to the period of the Franz-Keldysh oscillation while the period of the Franz-Keldysh oscillations stayed unchanged in type-I system. This phenomenon is explained by that the F was affected by the band bending effect caused by the spatially separated photo-excited carriers in the interface between GaAsSb and GaAs. The F changed linearly as a function of square root of excitation power as expected for the F. Moreover, F was calculated using fast Fourier transform method for a qualitative analysis, which is in a good agreement with the theory of triangular well approximation.
14
Content available remote

Lattice Sitting of Platinum Atoms in Diluted SiGe Alloys

51%
Dobaczewski L., Bonde Nielsen K., Nylandsted Larsen A., Lundsgaard Hansen J., Gościński K., Peaker A.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
297-299
EN
In this report we present high-resolution spectra obtained with a use of the Laplace transform deep level transient spectroscopy for platinum diffused into dilute (0-5% of Ge) SiGe alloys. Very significant changes are observed in the spectra associated with the transition metals as the germanium content is altered. We interpret these spectra in terms of the configurations of silicon and germanium atoms surrounding the transition metal. In order to explain the observed behaviour both the first and second nearest neighbour shells are considered.
15
Content available remote

Hybrid Organic/ZnO p-n Junctions, with n-Type ZnO, Grown by Atomic Layer Deposition

51%
Łuka G., Krajewski T., Szczerbakow A., Łusakowska E., Kopalko K., Guziewicz E., Wachnicki Ł., Szczepanik A., Godlewski M., Fidelus J.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue 5
1229-1234
EN
We report on fabrication of hybrid inorganic-on-organic thin film structures with polycrystalline zinc oxide films grown by atomic layer deposition technique. ZnO films were deposited on two kinds of thin organic films, i.e. pentacene and poly(dimethylosiloxane) elastomer with a carbon nanotube content (PDMS:CNT). Surface morphology as well as electrical measurements of the films and devices were analyzed. The current density versus voltage (I-V) characteristics of ITO/pentacene/ZnO/Au structure show a low-voltage switching phenomenon typical of organic memory elements. The I-V studies of ITO/PDMS:CNT/ZnO/Au structure indicate some charging effects in the system under applied voltages.
16
Content available remote

Thin Film ZnO as Sublayer for Electric Contact for Bulk GaN with Low Electron Concentration

51%
Grzanka S., Łuka G., Krajewski T., Guziewicz E., Jachymek R., Purgal W., Wiśniewska R., Sarzyńska A., Bering-Staniszewska A., Godlewski M., Perlin P.
Acta Physica Polonica A
|
2011
|
vol. 119
|
issue 5
672-674
EN
Fabrication of low resistivity ohmic contacts to N polarity gallium nitride crystal is an important issue for the construction of the vertical current flow devices like laser diodes and high brightness light emitting diodes. Gallium nitride is a challenging material because of the high metal work function required to form a barrier-free metal-semiconductor interface. In practice, all useful ohmic contacts to GaN are based on the tunneling effect. Efficient tunneling requires high doping of the material. The most challenging task is to fabricate high quality metal ohmic contacts on the substrate because the doping control is here much more difficult that in the case of epitaxial layers. In the present work we propose a method for fabricating low resistivity ohmic contacts on N-side of GaN wafers grown by hydride vapor phase epitaxy. These crystals were characterized by a n-type conductivity and the electron concentration of the order of 10^{17} cm^{-3}. The standard Ti/Au contact turned out to be unsatisfactory with respect to its linearity and resistance. Instead we decided to deposit high-n type ZnO layers (thickness 50 nm and 100 nm) prepared by atomic layer deposition at temperature of 200°C. The layers were highly n-type conductive with the electron concentration in the order of 10^{20} cm^{-3}. Afterwards, the metal contact to ZnO was formed by depositing Ti and Au. The electrical characterization of such a contact showed very good linearity and as low resistance as 1.6 × 10^{-3} Ω cm^2. The results indicate advantageous properties of contacts formed by the combination of the atomic layer deposition and hydride vapor phase epitaxy technology.
17
Content available remote

Transition Metal-Related Centres in Silicon Studied by High-Resolution Deep Level Transient Spectroscopy

51%
Dobaczewski L., Kamiński P., Kozłowski R., Surma M.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 4
703-706
EN
High-resolution Laplace-transform deep level transient spectroscopy tech­nique has been used to study a fine structure in the carrier emission process for transition metal- and thermal donors-related defects in silicon. For the case of the transition metal centres the method revealed the fine structure when the defect has a similar emission characteristics to other defects in the crystal. The method also demonstrated the complex emission process for the thermal donors.
18
Content available remote

Megagauss Cyclotron Resonance and Quantum Hall Effect of 2D Electron Gas in HgCdMnTe

51%
Grabecki G., Takeyama S., Dietl T., Takamasu T., Shimamotο Y., Miura N.
Acta Physica Polonica A
|
1995
|
vol. 88
|
issue 4
731-734
EN
Two-dimensional electron gas adjacent to a grain boundary in bicrystal of narrow-gap semiconductor p- Hg_{0.79}Cd_{0.19}Mn_{0.02}Te has been studied under ultra strong impulse magnetic fields (up to 140 T). Both cyclotron resonance and quantum Hall effect are measured for the same samples. The values of the resonance fields point to strong nonparabolicity. A broadening of the line is interpreted in terms of an intersubband mixing that occurs for the upper Landau level. A steep increase in the linewidth in the field range 20-30 T, which coincides with a strong decrease in the Hall resistance is assigned to the field-induced metal-insulator transition in our system.
19
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Fabrication and Characterization of Photosensitive n-CdO/p-InSe Heterojunctions

51%
Kudrynskyi Z., Kovalyuk Z., Katerynchuk V., Khomyak V., Orletsky I., Netyaga V.
Acta Physica Polonica A
|
2013
|
vol. 124
|
issue 4
720-723
EN
Photosensitive n-CdO/p-InSe heterojunctions were developed and studied for the first time. The heterojunctions were fabricated by dc reactive magnetron sputtering of CdO thin films onto the freshly cleaved p-InSe single-crystal substrates (0 0 1). Surface morphology of the obtained films was studied by means of atomic force microscopy. From the X-ray diffraction result it is shown that the CdO film is polycrystalline with cubic structure. The mechanisms of current transport through the space-charge region under forward and back biases were established by investigation of temperature dependences of the I-V characteristics. The main photoelectric parameters and the photosensitivity spectra were measured at room temperature.
20
Content available remote

Electrical Characteristics and Temperature Dependence of Photovoltaic Parameters of GaInAsSb Based TPV Diode

51%
Kucur B., Ahmetoglu M., Andreev I., Kunitsyna E., Mikhailova M., Yakovlev Y.
Acta Physica Polonica A
|
2016
|
vol. 129
|
issue 4
767-769
EN
In this paper, electrical characterization of low bandgap GaInAsSb based thermophotovoltaic (TPV) diodes were investigated, as well as the temperature dependence of photovoltaic parameters such as short circuit current (I_{sc}) and open circuit voltage (V_{oc}). Investigation of the dark current mechanisms of the structure was carried out at several temperatures. The effect of light intensity on current-voltage characteristics was also investigated.
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