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  1. 26 Acta Physica Polonica A

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  1. 2 Skorupa W.

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1
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Structural Changes in Flash Lamp Annealed Amorphous Si Layers Probed by Slow Positron Implantation Spectroscopy

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Anwand W., Schumann T., Brauer G., Skorupa W., Xiong S., Wu C., Gebel T.
Acta Physica Polonica A
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2008
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vol. 113
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issue 5
1273-1278
EN
Flash lamp annealing was applied to the modification of thin amorphous Si layers on SiO_2 and glass. Slow positron implantation spectroscopy was used for the characterisation of the microstructure before and after flash lamp annealing. Changes in the structure down to a depth of some micrometres below the surface observed with slow positron implantation spectroscopy will be presented and discussed.
2
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Fabrication of High-Density GaN Nanowires through Ammoniating Ga_2O_3/Nb Films

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Zhuang H., Li B., Zhang S., Zhang X., Xue C., Wang D., Shen J.
Acta Physica Polonica A
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2008
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vol. 113
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issue 2
723-730
EN
High-density GaN nanowires were successfully synthesized on Si(111) substrates through ammoniating Ga_2O_3/Nb films under flowing ammonia atmosphere at 950°C. The as-synthesized GaN nanowires are characterized by X-ray diffraction, selected-area-electron diffraction, Fourier transform infrared, scanning electron microscopy, and field-emission transmission electron microscopy. The results show that the synthesized nanowires are single-crystal hexagonal wurtzite GaN with diameters ranging from 30 to 100 nm and lengths up to several microns. The photoluminescence spectra measured at room temperature only exhibit a strong and broad emission peak at 367.8 nm. Finally, the growth mechanism of GaN nanowires is discussed.
3
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Optical Investigation of ZnO Nanowires

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Martínez-Criado G., Hernández-Vélez M., Letard I., Cros A., Cantarero A., Mínguez-Bacho I., Susini J., Tucoulou R., Sans J., Sanz R., Vázquez M.
Acta Physica Polonica A
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2010
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vol. 117
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issue 2
369-373
EN
In this study we report the application of synchrotron X-ray fluorescence, photoluminescence and Raman scattering techniques to the analysis of the incorporation of impurities in unintentionally doped ZnO nanowires. Highly ordered one-dimensional ZnO arrays were fabricated by an oxidation process of Zn metal electrodeposited in nanoporous anodic alumina template. X-ray fluorescence data show the contribution of residual elements into the ZnO nanowires growth. A rough analytical quantification of the main light and heavy chemical contents derives impurity concentrations below 1%. The optical efficiency of ZnO nanowires is strongly affected by non-radiative centers up to temperatures as low as 100 K. The photoluminescence was found to be totally dominated by optical transitions associated with the anodic alumina template. Finally, the Raman scattering provides no evidence of local vibrational modes or secondary phases, but it shows the unambiguous signature of the ZnO hexagonal phase.
4
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Self-Limiting Growth of GaN at Low Temperatures

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Ozgit C., Donmez I., Biyikli N.
Acta Physica Polonica A
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2011
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vol. 120
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issue 6A
A-55-A-57
EN
GaN thin films were deposited in a self-limiting fashion at low temperatures. Films were deposited on Si substrates by plasma-enhanced atomic layer deposition using trimethylgallium (TMG) or triethylgallium (TEG) as the group-III, and ammonia (NH_3) as the group-V precursors. TMG and TEG saturations were observed at 185 and 150°C, for doses starting from 0.015 and 1 s, respectively. Constant deposition rates of ≈ 0.51 and ≈ 0.48 Å/cycle were obtained within the temperature ranges of 250-350 and 150-350C for TMG- and TEG-based plasma-enhanced atomic layer deposition processes. Oxygen contents of the films were high ( ≈ 20 at.%) as determined by X-ray photoelectron spectroscopy.
5
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Electron Microscopy of Cracks in In_{x}Ga_{1-x}As/GaAs(001) Multi-Quantum Wells

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Atici Y., Yildiz K., Akgul U.
Acta Physica Polonica A
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2015
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vol. 127
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issue 3
859-862
EN
We studied cracks in two different In_{x}Ga_{1-x}As/GaAs(001) multi-quantum-well structures by electron microscopy. Transmission and scanning electron microscopy analyses of the sample-1 revealed that the epilayers associated with cracks. Detailed experimental works on the cracks were carried out by conventional and high-resolution electron microscopy. It was found that the epilayers were very effective on stopping the cracks in sample-1. Many dislocations were observed around the cracks and cracks tips. SEM images showed that the cracks formed an orthogonal set array accompanying with slits and pits. However, there were not observed any cracks in the sample-2.
6
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Experimental Investigation of Resistive Sensor for High Power Millimetre Wave Pulse Measurement

100%
Simniškis R., Dagys M., Kancleris Ž., Tamošiūnas V.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
1091-1094
EN
An experimental investigation of a high power millimetre wave pulse sensor is presented. Two groups of sensors with a flat frequency response were fabricated according to results of the optimisation. The frequency response and voltage standing wave ratio were measured and compared with results of the electrodynamical simulations. The largest measured sensitivity variation of the best sensors within waveguide frequency range was±8%. The reasonable agreement between measured and simulated values of the sensitivity was obtained.
7
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Effect of Doping on Ga_{1-x}Al_{x}As Structural Properties

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Bąk-Misiuk J., Domagała J., Paszkowicz W., Trela J., Żytkiewicz Z. R., Leszczyński M., Regiński K., Muszalski J., Härtwig J., Ohler M.
Acta Physica Polonica A
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1997
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vol. 91
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issue 5
911-917
EN
The microstructure of Ga_{1-x}Al_{x}As layers was studied using methods of high resolution diffractometry and topography. Mapping out the reciprocal space in the vicinity of 004 reciprocal lattice points shows a difference in diffuse scattering between doped and undoped layers. This result is attributed to a difference in a point-defect density. From the measurements of lattice parameters at different temperature it was found that the thermal expansion coefficients for the doped layers are higher than for the undoped ones. This phenomenon is attributed to the change of the anharmonic part of lattice vibrations by free electrons or/and point defects.
8
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Formation of Porous n-A_3B_5 Compounds

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Šimkiene I., Kindurys A., Treideris M., Sabataityte J.
Acta Physica Polonica A
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2008
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vol. 113
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issue 3
1085-1090
EN
Porous layers of A_3B_5 compounds were formed on n-type wafers by electrochemical anodic etching. The morphology of nanostructured layers was studied by scanning electron microscopy and atomic force microscopy techniques. The optimal conditions of the formation of porous layers were determined by varying the composition of etching solution, current density and etching time. Large area (1.5×1.5 cm^2) porous layers of uniform porosity were produced by anodization process of n-type A_3B_5 semiconductors,
9
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Determination of the Temperature Dependent Thermal Expansion Coefficients of Bulk AlN by HRXRD

100%
Kröncke H., Figge S., Hommel D., Epelbaum B.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1193-1200
EN
We measured the lattice constants of bulk aluminum nitride crystals at various temperatures by high resolution X-ray diffraction. By the use of a high temperature chamber and a X-ray cryostat a temperature regime from 20 to 1210 K was available. Furthermore, the measured data were fitted by Einstein- and Debye models which yield reliable parameters for the calculation of the thermal expansion coefficients of AlN.
10
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Type-I and Type-II Confinement in Quantum Dots: Excitonic Fine Structure

100%
Křápek V., Klenovský P., Šikola T.
Acta Physica Polonica A
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2016
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vol. 129
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issue 1a
A-66-A-69
EN
We have theoretically studied type-I and type-II confinement in InAs quantum dots with GaAs_{1-y}Sb_y capping layer. The character of the confinement can be adjusted by the Sb content. We have found that upon the transition from type-I to type-II confinement the hole wave functions change the topology from a compact shape to a two-segment shape, resulting in the complex changes in the exciton fine structure splitting with zero values at narticular compositions. Additionally, a high exciton radiative recombination probability is preserved even in type-II. This allows to design strongly luminescent quantum dots with naturally low fine structure splitting, which could serve as sources of entangled photon pairs for quantum communication.
11
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Elastic-Plastic Transition in MBE-Grown GaSb Semiconducting Crystal Examined by Nanoindentation

100%
Majtyka A., Trębala M., Tukiainen A., Chrobak D., Borgieł W., Räisänen J., Nowak R.
Acta Physica Polonica A
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2016
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vol. 130
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issue 4
1131-1133
EN
The present paper concerns the elastic-plastic nanodeformation of Te-doped GaSb crystals grown by molecular beam epitaxy on the n-type of GaSb substrate. The conventional analysis of nanoindentation data obtained with sharp triangular (Berkovich) and spherical tip revealed the elastic modulus (E=83.07± 1.78 GPa), hardness (H=5.19±0.25 GPa) and "true hardness" (H_{T}=5.73±0.04 GPa). The registered pop-in event which indicates the elastic-plastic transition in GaSb crystal points towards the corresponding yield strength (σ_{Y}=3.8±0.1 GPa). The origin of incipient plasticity in GaSb crystal is discussed in terms of elastic-plastic deformation energy concept.
12
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Growth Control of N-Polar GaN in Plasma-Assisted Molecular Beam Epitaxy

100%
Mizerov A., Jmerik V., Kaibyshev V., Komissarova T., Masalov S., Sitnikova A., Ivanov S.
Acta Physica Polonica A
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2008
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vol. 114
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issue 5
1253-1258
EN
The paper reports on plasma-assisted MBE growth of good quality N-face GaN layers directly on c-Al₂O₃ substrates. Growth kinetics under different growth conditions (substrate temperature, Ga to activated nitrogen flux ratio, etc.) during deposition of GaN(0001) and GaN(0001̅) both by the ammonia-based MBE or plasma-assisted MBE was studied. It was found that atomically smooth surface of 1 μm thick GaN(0001̅) films can be achieved by plasma-assisted MBE at the relatively high substrate temperature T_S ≈ 760°C and Ga to activated nitrogen flux ratio F_Ga/F_N* ≈ 1.8.
13
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Properties and Characterization of ALD Grown Dielectric Oxides for MIS Structures

100%
Gierałtowska S., Sztenkiel D., Guziewicz E., Godlewski M., Łuka G., Witkowski B., Wachnicki Ł., Łusakowska E., Dietl T., Sawicki M.
Acta Physica Polonica A
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2011
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vol. 119
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issue 5
692-695
EN
We report on an extensive structural and electrical characterization of undergate dielectric oxide insulators Al_2O_3 and HfO_2 grown by atomic layer deposition. We elaborate the atomic layer deposition growth window for these oxides, finding that the 40-100 nm thick layers of both oxides exhibit fine surface flatness and required amorphous structure. These layers constitute a base for further metallic gate evaporation to complete the metal-insulator-semiconductor structure. Our best devices survive energizing up to ≈ 3 MV/cm at 77 K with the leakage current staying below the state-of-the-art level of 1 nA. At these conditions the displaced charge corresponds to a change of the sheet carrier density of 3 × 10^{13} cm^{-2}, which promises an effective modulation of the micromagnetic properties in diluted ferromagnetic semiconductors.
14
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Calculation Method for the Bandgap of Antimonide Based Multicomponent Alloys

100%
An N., Liu C., Fan C., Dong X., Song Q.
Acta Physica Polonica A
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2018
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vol. 133
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issue 1
118-120
EN
As the most important material parameter of semiconductor, bandgap is necessary to be investigated to meet the design requirements of the high-performance optoelectronic devices. A new method of is proposed to calibrate the bandgap of antimonide based multi-component alloys with considering the effect of spin-orbit splitting off bands and the doublet degeneracy of valance band on the bandgaps of Sb-containing materials. A correction factor is introduced in the conventional calculation, and the spin-orbit splitting method is proposed. Besides, the In_xGa_{1-x}As_ySb_{1-y} films with different compositions are grown on GaSb substrates by molecular beam epitaxy, and the corresponding bandgaps are obtained by photoluminescence to test the accuracy and reliability of this new method. An error rate analysis reveals that the α calculated by the spin-orbit splitting correction method is decreased to 2%, almost one order of magnitude smaller than the Moon method, which means that the new method can calculate the antimonide multicomponent more accurately with some applicability. This work can give a reasonable interpretation for the reported results and beneficial to tailor the antimonides properties and optoelectronic devices.
15
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Photoreflectance of Epitaxial InGaAs Quantum Rods

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Nedzinskas R., Karpus V., Čechavičius B., Kavaliauskas J., Valušis G., Li L., Khanna S., Linfield E.
Acta Physica Polonica A
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2011
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vol. 119
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issue 2
164-166
EN
Photoreflectance spectroscopy and photoluminescence have been used to study the optical properties and electronic structure of InGaAs quantum rods grown by molecular beam epitaxy. Spectral features associated with interband optical transitions localized in the quantum rod and the surrounding quantum well regions are examined. Experimental results are compared with calculations performed within the envelope function approximation. A red shift of the quantum rod- and a blue shift of the quantum well-related optical transitions, along with a significant increase in PL intensity have been observed if an As_4 source is used instead of an As_2 source during the molecular beam epitaxial growth.
16
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Comparative Study of the Molecular Beam Epitaxial Growth of InAs/GaSb Superlattices on GaAs and GaSb Substrates

100%
Benyahia D., Kubiszyn Ł., Michalczewski K., Kębłowski A., Martyniuk P., Piotrowski J., Rogalski A.
Acta Physica Polonica A
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2017
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vol. 132
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issue 2
322-324
EN
Short period type-II 10 ML InAs/10 ML GaSb superlattices epilayers (λ_{cut-off}=5.4 μm) have been grown on near lattice matched GaSb (001) substrate and on lattice mismatched GaAs (001) substrate, by molecular beam epitaxy system. In the case of growing on GaAs substrate, GaSb buffer layer was grown in order to reduce the lattice mismatch of 7.5% between GaAs substrate and InAs/GaSb superlattices. X-ray diffraction characterization shows a good crystalline quality for both samples, with a full width at half maximum of 190 arcsec and 156 arcsec for the zeroth-order peak of the superlattice grown on GaAs and on GaSb substrate, respectively. The Nomarski microscopy revealed a shiny surface for both samples with a root main square of surface roughness of 9 nm and 11 nm on the case of growing on GaSb and GaAs substrate, respectively.
17
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Optical Properties of Multi-Stacked InAs Quantum Dots Embedded in GaAs/InGaAs Strained Layer and its Annealing Behaviors

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Kim D., Kim G., Jeon S., Cho M., Choi H., Kim M., Lee D., Kim J., Kim J., Eom G., Leem J.
Acta Physica Polonica A
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2010
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vol. 117
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issue 6
941-944
EN
Multi-stacked InAs QDs embedded in ten periods of GaAs/In_{0.1}Ga_{0.9}As strained layers were grown by MBE and their optical properties were investigated by using PL spectroscopy. For the QDs embedded in ten periods of GaAs/In_{0.1}Ga_{0.9}As strained layers, the PL intensity is enhanced about 4.7 times and a narrower FWHM of 26 meV is observed compared to those of the conventional multi-stacked QDs. The PL spectra of the InAs QDs show blue-shifts of about 50 meV with increasing annealing temperature up to 850°C. At annealing temperature of 600°C, the FWHM of the PL peak is reduced to 16 meV and PL intensity is enhanced compared to those of the as-grown sample, which indicates improvement of size uniformity and crystal quality of the QDs.
18
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Formation of Uniform Germanium Islands on Silicon Substrate Using Nickel as Catalyst by Thermal Evaporation Method

100%
Jumidali M., Hashim M., Abdul Aziz A., Abd Rahim A.
Acta Physica Polonica A
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2015
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vol. 127
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issue 4
1068-1071
EN
Uniform germanium islands (GIs) were grown on Si (100) using a nickel layer as catalyst through the physical vapor deposition of germanium (Ge) powder at 1000°C at different deposition times. Prior to the deposition of Ge layer, nickel (Ni) catalyst was deposited on silicon substrates via radio frequency magnetron sputtering technique. Scanning electron microscopy results showed that the increase in deposition time resulted in a variation in surface morphology. Energy dispersive X-ray spectrometer analysis found that the GI samples composed of Ni element indicating the role of Ni in uniform Ge islands formation. The X-ray diffraction pattern spectra revealed that the GIs exhibited a Ge cubic structure and the intensity of Ge peaks varies with deposition time. In-plane strain indicated that the strain caused by the substrate is tensile and changed to compressive strain at the longer deposition time. The Raman spectra exhibited a red shift in the Ge-Ge peak, compared with the bulk Ge, as a result of compressive strain of the GIs. Fourier transform infrared spectrum analysis also indicated that the optical band gap Eg values of GIs can be varied by deposition time.
19
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Materials Technology for GaSb-Based optoelectronic Devices

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Piotrowska A., Kamińska E., Piotrowski T., Piskorski M., Guziewicz M., Papis E., Gołaszewska-Malec K., Kasjuniuk S.
Acta Physica Polonica A
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1996
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vol. 90
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issue 5
903-906
EN
A study is made of surface preparation, metallization, patterning and dielectric deposition with the aim of developing process technology for GaSb-based photonic devices.
20
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Evolution of InAs Quantum Dots during Annealing Process

100%
Guo-zhi J., Jiang-hong Y., Yong-chun S., Xiao-dong X., Pi-Biao
Acta Physica Polonica A
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2008
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vol. 114
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issue 4
919-923
EN
InAs quantum dots were grown by molecular beam epitaxy in the Stranski-Krastanow growth mode and annealed under N_2 atmospheres at different temperatures. The evolution of quantum dots with the annealing temperature increasing were slightly different with the results reported in the literature. Atomic force microscopy investigations of quantum dots uncapped layer show a size initial increase followed by a prompt decrease as annealing temperature increases. It was found that the photoluminescence signal on quantum dots capped with GaAs layer was first slightly red-shifted and then blue-shifted with an increase in annealing temperature. The blue-shift can be attributed to In/Ga interdiffusion in annealing process. Red-shift of optical features indicates the change of the quantum dots compostion, size, and strain from the barrier.
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