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  1. 43 Acta Physica Polonica A

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  1. 11 Godlewski M.

  2. 9 Guziewicz E.

  3. 7 Paszkowicz W.

  4. 6 Łusakowska E.

  5. 5 Karczewski G.

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1
Publication available in full text mode
Content available

Cd(Mg)Se Single Layers and CdSe/CdMgSe Heterostructures Grown by Molecular Beam Epitaxy on InAs(001) Substrates

100%
Kaygorodov V., Sorokin V., Sedova I., Nekrutkina O., Sorokin S., Shubina T., Toropov A., Ivanov S.
Acta Physica Polonica A
|
2001
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vol. 100
|
issue 3
443-450
EN
We report on molecular beam epitaxy of CdSe/CdMgSe heterostructures on InAs(001) substrates and studies of their optical and structural properties. The CdMgSe energy gap versus composition dependence is determined. The zinc-blende MgSe band-gap energy and optical bowing parameter are estimated to be 4.05 eV and 0.2 eV, respectively. The CdSe quantum wells embedded into CdMgSe barriers demonstrate intense photoluminescence. Effective mass approximation calculations of electron-heavy hole optical transitions in CdSe quantum well are in a good agreement with the experimental data obtained.
2
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Surface Related Electronic States on CdTe(110) Observed by Means of Optical Spectroscopy

63%
Kowalski B. J., Orłowski B. A., Cricenti A.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
1005-1009
EN
Surface differential reflectivity together with photoemission and Auger electron spectroscopies have been applied to observe and identify optical transitions among surface related states on CdTe(110) surfaces. The strongest contributions to the band of optical transitions have been revealed at the photon energies of 2.8, 3.4, and 3.9 eV. Their correspondence to excitations from the occupied S1 band to the unoccupied U1 one at the Γ, Χ and Χ' points of the surface Brillouin zone is discussed.
3
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Optical and Electrical Properties of Highly Doped ZnO:Al Films Deposited by Atomic Layer Deposition on Si Substrates in Visible and Near Infrared Region

63%
Romanyuk V., Dmitruk N., Karpyna V., Lashkarev G., Popovych V., Dranchuk M., Pietruszka R., Godlewski M., Dovbeshko G., Timofeeva I., Kondratenko O., Taborska, M., Ievtushenko A.
Acta Physica Polonica A
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2016
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vol. 129
|
issue 1a
A-36-A-40
EN
Optical properties of ZnO films doped by Al in the range 0.5 to 7 at.% and deposited by atomic layer deposition were studied in visible and infrared spectral range. Spectral dependences of film optical permittivity were modeled with the Lorentz-Drude approximation resulting in ZnO:Al plasma frequency and plasma damping parameters. We observed changing electron effective mass from 0.29m₀ to 0.5m₀ with increasing electron concentration in the range (0.9-4) × 10²⁰ due to the phenomenon of conduction band non-parabolicity. Comparing the results of optical and electrical investigations we can see that the main scattering mechanism is the scattering on grain boundaries (its contribution is about 60%).
4
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Optically Pumped Low Threshold ZnSe Based Lasers with 2.8 ML CdSe Active Region

63%
Sorokin S., Toropov A., Shubina T., Lebedev A., Sedova I., Ivanov S., Waag A.
Acta Physica Polonica A
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1998
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vol. 94
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issue 3
539-544
EN
Room-temperature optically pumped (Zn,Mg)(S,Se)/(Zn,Cd)Se laser structures have been grown by molecular beam epitaxy. Using of alternatively-strained short-period superlattice waveguide results in low threshold power density values over the whole blue-green (470-520 nm) wavelength range. Incorporation of CdSe fractional monolayer active region provides more than fourfold further decrease in threshold with respect to quantum well laser structure. Optical and structural properties of laser structure with 2.8 monolayer CdSe are discussed in detail.
5
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Exciton States in Type-II ZnSe/BeTe Quantum Wells

63%
Platonov A. V., Yakovlev D. R., Zehnder U., Kochereshko V. P., Ossau W., Fischer F., Litz T., Waag A., Landwehr G.
Acta Physica Polonica A
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1997
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vol. 92
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issue 5
953-957
EN
We present an optical investigation of novel heterostructures based on beryllium chalcogenides with a type-I and type-II band alignment. In the type-II quantum well structures (ZnSe/BeTe) we observed a strong exciton transition involving an electron confined in the conduction band well and a hole localized in the valence band barrier (both in ZnSe layer). This transition is drastically broadened by the temperature increase due to enhanced exciton-acoustic phonon interaction.
6
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Half-Parabolic Quantum Wells of Diluted Magnetic Semiconductor Cd_{1-x}Mn_{x}Te

63%
Kutrowski M., Wojtowicz T., Cywiński G., Karczewski G., Janik E., Dynowska E., Kossut J., Kossacki P., Fiederling R., Pfeuffer-Jeschke A., Ossau W.
Acta Physica Polonica A
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1997
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vol. 92
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issue 5
887-890
EN
We report on magnetooptical studies of MBE-grown half-parabolic CdTe/Cd_{x}Mn_{1-x}Te quantum well structures. The value of the valence band offset Q_{v}=0.4 ± 0.05 was determined by comparing energies of optical transitions in the absence of a magnetic field with model calculations. This value was verified by fitting the observed spin splitting of the lowest heavy hole (hh) state. We discuss also the temperature dependence of Q_{v}.
7
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Structural and Optical Studies of CdTe/ZnTe Superlattices with Ultrathin ZnTe Layers

63%
Mariette H., Jouneau P., Pelekanos N., Tardot A., Feuilet G., Magnea N.
Acta Physica Polonica A
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1993
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vol. 84
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issue 3
423-433
EN
Spatially selective introduction of ultrathin ZnTe layers (1 to 3 mono-layers) into CdTe allows the study of special superlattice structure, corresponding to a monomolecular plane-host crystal system. Particular attention is given to the strain state control of the inserted ZnTe monolayer. High resolution electron microscopy is used to measure the local lattice distortion: the method yields the location and the total amount of Zn per period, and the results are compared with X-ray diffraction data. Optical properties of these superlattices are also presented. All results show the ability to control ultrathin pseudomorphic layers of ZnTc within CdTe, with limited Zn segregation, and of high crystalline and optical quality. In addition, they can be fitted within the framework of elasticity theory for the structural data, and of a finite quantum well model for the optical ones, even in the ultimate limit of only one nominal ZnTe monolayer.
8
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δ-Doped CdTe/Cd_{1-x}Mn_{x}Te Multiple Quantum Wells Investigated by Photoreflectance Spectroscopy

63%
Sitarek P., Misiewicz J., Karczewski G., Wojtowicz T., Kossut J.
Acta Physica Polonica A
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1995
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vol. 88
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issue 5
901-904
EN
Room temperature photoreflectance spectroscopy was used to investigate CdTe/Cd_{1-x}Mn_{x}Te multiple quantum wells grown by MBE. Structures were indium δ-doped into the well or into the barrier. The value of heavy and light hole subbands splitting was measured and compared to the calculated ones. The influence of the position of δ-doping on the measured spectra was shown.
9
Publication available in full text mode
Content available

Effect of Zn:Se Ratio on the Properties of Sprayed ZnSe Thin Films

63%
Öztaş M., Bedir M., Bakkaloğlu Ö., Ormancı R.
Acta Physica Polonica A
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2005
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vol. 107
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issue 3
525-534
EN
The effect of Zn:Se ratio on the photoconducting properties of ZnSe thin films has been studied. The ZnSe thin films have been deposited onto glass substrates by the spray pyrolysis method, the substrate temperature kept at 430ºC using mixed aqueous solutions of ZnCl_2 and SeO_2 with different Zn:Se ratios. Their electrical, structural, and photoconductivity properties have been studied. The values of optical bandgap have been determined from the absorption spectra.
10
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Optical Study of an Asymmetric Double Quantum Well System: CdTe/CdMnTe

51%
Lawrence I., Feuilet G., Tuffigo H., Bodin C., Cibert J., Rühle W.
Acta Physica Polonica A
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1993
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vol. 84
|
issue 4
637-640
EN
Carrier tunneling through CdMnTe barriers of different thicknesses is investigated in CdTe/CdMnTe asymmetric double quantum wells. Steady-state photoluminescence at 1.8 K and time-resolved photoluminescence experiments between 10 K and 50 K were performed.
11
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Influence of Thermal Process on Physical Properties of ZnO Films Prepared by Spray Pyrolysis

51%
Gencyilmaz O., Atay F., Akyuz I.
Acta Physica Polonica A
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2014
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vol. 126
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issue 6
1331-1337
EN
ZnO films were deposited on glass substrates by ultrasonic spray pyrolysis technique at a substrate temperature of 300 ± 5°C. All of the films have been annealed at 500°C temperature for different time (1, 2, and 3 h) to improve the optical, electrical and surface properties. The effect of annealing time on the films of physical properties has been investigated. UV-Vis spectrophotometer has been used for transmittance measurements. Also, band gap values of the films have been determined by optical method. Atomic force microscopy has been used to have information the surface morphology and roughness values of the films. Thicknesses, refractive index and extinction coefficient values of the films have been determined by spectroscopic ellipsometry technique. The electrical conduction mechanisms and resistivity of the films were investigated using two probe technique. After all the investigations it was concluded that annealing time has a dramatic effect especially on the surface, optical properties and electrical resistivity values of ZnO films. From the results of these investigations, the application potential of the films for solar cell devices as transparent electrode was searched.
12
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(Zn,Cu)O Films by Atomic Layer Deposition - Structural, Optical and Electric Properties

51%
Łukasiewicz M., Witkowski B., Wachnicki Ł., Kopalko K., Gierałtowska S., Wittlin A., Jaworski M., Guziewicz E., Godlewski M.
Acta Physica Polonica A
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2011
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vol. 120
|
issue 6A
A-34-A-36
EN
ZnCuO thin films have been deposited on silicon, glass and quartz substrates by atomic layer deposition method, using reactive organic precursors of zinc and copper. As zinc and copper precursors we applied diethylzinc and copper(II) acetyloacetonate. Structural, electrical and optical properties of the obtained ZnCuO layers are discussed based on the results of scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, atomic force microscopy, the Hall effect and photoluminescence investigations.
13
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Luminescence Decay in Deep Quantum Wells CdTe/Cd_{0.5}Mn_{0.5}Te at Room Temperature

51%
Kowalczyk L., Fancey S., Buller G. S., Massa J. S., Kutrowski M., Janik E., Karczewski G., Wojtowicz T., Zakrzewski A. K., Kossut J.
Acta Physica Polonica A
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1995
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vol. 87
|
issue 2
508-513
EN
Time-resolved photoluminescence was used to study exciton recombi­nation in deep CdTe/Cd_{0.5}Mn_{0.5}Te single quantum well. The width of the investigated well was 100 A. The study was performed at room temperature. The lifetime of the exciton determined in this work has a value comparable to that observed in shallow CdTe/Cd_{0.85}Mn_{0.15}Te quantum wells. A strong enhancement of the photoluminescence decay time with increasing intensity of the exciting laser beam is observed which is indicative of saturation of the non-radiative recombination centers.
14
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From Magnetic Polarons to Ferromagnetism

51%
Dietl T.
Acta Physica Polonica A
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1998
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vol. 94
|
issue 2
111-123
EN
A brief overview is given on selected effects of the exchange coupling between effective mass electrons and localized spins in II-VI semiconductors containing Mn ions. In the case of a carrier or exciton trapped by an impurity or defect, the exchange interaction leads to zero-field spin-splitting. The current theory of such complexes, known as bound magnetic polarons, describes correctly their spectroscopic and thermodynamic properties as well as their formation dynamics. At the same time, a free magnetic polaron - a delocalized carrier accompanied by a traveling cloud of polarized spins - is not expected to exist for the actual values of the coupling constants. However, hole scattering by thermodynamic and static fluctuations is shown to affect significantly its energy. For a strong coupling, the corresponding renormalization has to be described by a non-perturbative approach. Finally, the influence of the carrier liquid upon the Mn spins is discussed. Here, either optical pumping or p-type doping may lead to a ferromagnetic order, both in bulk and layered structures. Because of a long-range character of the carrier mediated interactions, this ordering is not destroyed by the fluctuations, even in the reduced dimensionality systems.
15
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ZnCoO Films by Atomic Layer Deposition - Influence of a Growth Temperature οn Uniformity of Cobalt Distribution

51%
Łukasiewicz M., Witkowski B., Godlewski M., Guziewicz E., Sawicki M., Paszkowicz W., Łusakowska E., Jakieła R., Krajewski T., Kowalik I., Kowalski B.
Acta Physica Polonica A
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2009
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vol. 116
|
issue 5
921-923
EN
We report on the structural, electrical and magnetic properties of ZnCoO thin films grown by atomic layer deposition method using reactive organic precursors of zinc and cobalt. As a zinc precursor we applied either dimethylzinc or diethylzinc and cobalt(II) acetyloacetonate as a cobalt precursor. The use of these precursors allowed us the significant reduction of a growth temperature to 300°C and below, which proved to be very important for the growth of uniform films of ZnCoO. Structural, electrical and magnetic properties of the obtained ZnCoO layers will be discussed based on the results of secondary ion mass spectroscopy, scanning electron microscopy, energy dispersive spectroscopy, X-ray diffraction, atomic force microscopy, Hall effect and SQUID investigations.
16
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Exciton Trions in II-VI Heterostructures

51%
Cox R., Huard V., Kheng K., Lovisa S., Miller R., Saminadayar K., Arnoult A., Cibert J., Tatarenko S., Potemski M.
Acta Physica Polonica A
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1998
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vol. 94
|
issue 2
99-109
EN
Optical spectra associated with transitions that create or annihilate charged excitons X^{-} or X^{+} can be observed in quantum well heterostructures containing an electron gas or a hole gas, respectively. A review is given of properties of trion states in CdTe quantum wells in zero field and of the magnetic field-dependence of the circular polarization and oscillator strength of the trion optical resonance. The possibility that disorder is needed to stabilise trion states in concentrated 2D electron or hole systems is discussed.
17
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ZnO by ALD - Advantages of the Material Grown at Low Temperature

51%
Guziewicz E., Godlewski M., Krajewski T., Wachnicki Ł., Łuka G., Paszkowicz W., Domagała J., Przeździecka E., Łusakowska E., Witkowski B.
Acta Physica Polonica A
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2009
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vol. 116
|
issue 5
814-817
EN
The 3D-architecture is a prospective way in miniaturization of electronic devices. However, this approach can be realized only if metal paths are placed not only at the top, but also beneath the electronic parts, which imposes drastic temperature limitations for the electronic device processing. Therefore last years a lot of investigations are focused on materials which can be grown at low temperature with electrical parameters appropriate for electronic applications. Zinc oxide grown by the atomic layer deposition method is one of the materials of choice. We obtained ZnO-ALD films at growth temperature range between 100°C and 200°C, and with controllable electrical parameters. Free carrier concentration was found to scale with deposition temperature, so it is possible to grow ZnO films with desired conductivity without any intentional doping. We used correlation of electrical and optical parameters to optimize the deposition process. Zinc oxide layers obtained in that way have free carrier concentration as low as 10^{16} cm^{-3} and high mobility (10-50 cm^{2}/(Vs)), which satisfies requirements for a material used in three-dimensional memories.
18
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Luminescence of Zn_{x}Mg_{1-x}Se Layers Obtained by Thermal Diffusion of Mg into ZnSe and Zn_{x}Mg_{1-x}Se Epilayers Grown by Molecular Beam Epitaxy

51%
Bała W., Firszt F., Głowacki G., Gapiński A., Dzik J.
Acta Physica Polonica A
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1995
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vol. 87
|
issue 1
161-164
EN
This work deals with the study of photoluminescence properties of Zn_{x}Mg_{1-x}Se epilayers grown by molecular beam epitaxy on (001) GaAs and (111) ZnTe substrates and Zn_{x}Mg_{1-x}Se layers obtained by thermal diffusion of Mg into ZnSe single crystals. Luminescence spectra of Zn_{x}Mg_{1-x}Se layers are dominated by blue and violet emission bands with maxima positioned in the range of photon energies: 3.05-3.28 eV, 2.88-3.04 eV, 2.81 eV and 2.705 eV, depending on preparation conditions. In some samples the blue luminescence is observed up to room temperature.
19
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Optical Properties of Zn_{1-x}Mg_{x}Se Epilayers Studied by Spectroscopy Methods

51%
Głowacki G., Gapiński A., Derkowska B., Bała W., Sahraoui B.
Acta Physica Polonica A
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1998
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vol. 94
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issue 2
321-325
EN
Linear optical properties of the Zn_{1-x}Mg_{x}Se (0 ≤ x ≤ 0.4) alloys have been studied using reflectance, spectroscopic ellipsometry and photoluminescence measurements. The refractive indices of Zn_{1-x}Mg_{x}Se epilayers were investigated as a function of Mg composition (0 ≤ x ≤ 0.4). The energies of band gap E_{g} and spin-orbit splitting E_{g}+Δ, have been determined. These energies are shifted gradually to higher values with increasing Mg content.
20
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Extra-Low Temperature Growth of ZnO by Atomic Layer Deposition with Diethylzinc Precursor

51%
Kowalik I., Guziewicz E., Kopalko K., Yatsunenko S., Godlewski M., Wójcik A., Osinniy V., Krajewski T., Story T., Łusakowska E., Paszkowicz W.
Acta Physica Polonica A
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2007
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vol. 112
|
issue 2
401-406
EN
ZnO thin films were grown on silicon substrate by atomic layer deposition method. We explored double-exchange chemical reaction and used very volatile and reactive diethylzinc as a zinc precursor. These enables us to obtain zinc oxide thin films of high quality at extremely low growth temperature (90-200ºC). The films are polycrystalline as was determined by X-ray diffraction and show flat surfaces with roughness of 1-4 nm as derived from atomic force microscopy measurements. Photoluminescence studies show that an edge emission of excitonic origin is observed even at room temperature for all investigated ZnO layers deposited with the diethylzinc precursor.
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