CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, PL-01142 Wa... more CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, PL-01142 Warsaw, Poland International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw, Poland. Laboratoire Charles Coulomb, Université de Montpellier, Centre National de la Recherche Scientifique, F-34095 Montpellier, France. Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw, Poland. Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent’eva 13, Novosibirsk, 630090 Russia. Institute for Physics of Microstructures, Russian Academy of Sciences, N. Novgorod, 603950 Russia. WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
The finite element modeling is used to improve the accuracy of In composition determination by ta... more The finite element modeling is used to improve the accuracy of In composition determination by taking into account the two limiting factors in high resolution microscopy: strain relaxation and projection.
A new technique for studying extended defects and dislocation networks is proposed. The approach,... more A new technique for studying extended defects and dislocation networks is proposed. The approach, based upon the continuum theory of crystal defects, is employed for digital image processing of high-resolution transmission electron micrographs. The procedure starts ...
CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown usi... more CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.
The effect of Cu ion doping on the photoluminescence (PL) and magnetic behavior of ZnO/MgO and Zn... more The effect of Cu ion doping on the photoluminescence (PL) and magnetic behavior of ZnO/MgO and ZnO/oleic acid core/shell nanoparticles is investigated.
We report on Au catalyst-assisted molecular beam epitaxy growth and properties of pure ZnSe and Z... more We report on Au catalyst-assisted molecular beam epitaxy growth and properties of pure ZnSe and ZnSe/CdSe superlattice nanowires. In particular, we concentrate our attention on the morphological characterization by transmission and scanning electron microscopy of pure ZnSe NWs and we compare their optical properties with those of ZnSe/CdSe superlattice NWs fabricated at the same technological conditions.
ZnTe nanowires produced by molecular beam epitaxy via the vapour/liquid/solid mechanism were stud... more ZnTe nanowires produced by molecular beam epitaxy via the vapour/liquid/solid mechanism were studied by transmission electron microscopy. The wires grew along the ?111? directions pointing out of the (001)-oriented GaAs substrate. The length of the wires amounted to some microns depending on the growth time. The mean diameter ranged between 30 and 60 nm depending on the size of the
ABSTRACT MBE grown ZnTe/CdxZn1-xTe superlattices containing a high density of quantum dots have b... more ABSTRACT MBE grown ZnTe/CdxZn1-xTe superlattices containing a high density of quantum dots have been investigated by quantitative TEM methods. The Cd concentration in the superlattice was determined from local lattice parameter measured by digital processing of experimental HRTEM images. For the 15ML(ZnTe)/2ML(CdTe) superlattice, the density of quantum dots is 1.3x106 P-3. The dots are Cd rich islands of diameter from 6 to 8 nm and hights below 1.5 nm. The Cd concentration in islands centre was estimated to be between x=0.35 and x=0.85. Areas with ordering of QD were observed.
An arrangement of self-assembled GaN nanowires (NWs) grown by plasma-assisted molecular beam epit... more An arrangement of self-assembled GaN nanowires (NWs) grown by plasma-assisted molecular beam epitaxy on a Si(111) substrate is studied as a function of the temperature at which the substrate is nitridized before GaN growth. We show that the NWs grow with the c-axis perpendicular to the substrate surface independently of nitridation temperature with only a slight improvement in tilt coherency for high nitridation temperatures. A much larger influence of the substrate nitridation process on the in-plane arrangement of NWs is found. For high (850 °C) and medium (450 °C) nitridation temperatures angular twist distributions are relatively narrow and NWs are epitaxially aligned to the substrate in the same way as commonly observed in GaN on Si(111) planar layers with an AlN buffer. However, if the substrate is nitridized at low temperature (~150 °C) the epitaxial relationship with the substrate is lost and an almost random in-plane orientation of GaN NWs is observed. These results are correlated with a microstructure of silicon nitride film created on the substrate as the result of the nitridation procedure.
The structure of GaMnAs nanowires (NW) with nominal Mn concentration of up to 7 at% was investiga... more The structure of GaMnAs nanowires (NW) with nominal Mn concentration of up to 7 at% was investigated by transmission electron microscopy. The (Ga,Mn)As NW were grown on epiready GaAs(001) n-type wafers by molecular beam epitaxy. The crystal structure of the NW was determined to be zinc-blende. NW with Mn concentrations lower than 5 at% grow along the 111 direction. NW with higher Mn concentrations grow along the 110 direction and reveal a branching structure. The main nanowire and branches grow along the 110 directions belonging to only one {111} plane.
CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, PL-01142 Wa... more CENTERA Laboratories, Institute of High-Pressure Physics, Polish Academy of Sciences, PL-01142 Warsaw, Poland International Research Centre MagTop, Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw, Poland. Laboratoire Charles Coulomb, Université de Montpellier, Centre National de la Recherche Scientifique, F-34095 Montpellier, France. Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw, Poland. Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, pr. Akademika Lavrent’eva 13, Novosibirsk, 630090 Russia. Institute for Physics of Microstructures, Russian Academy of Sciences, N. Novgorod, 603950 Russia. WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
The finite element modeling is used to improve the accuracy of In composition determination by ta... more The finite element modeling is used to improve the accuracy of In composition determination by taking into account the two limiting factors in high resolution microscopy: strain relaxation and projection.
A new technique for studying extended defects and dislocation networks is proposed. The approach,... more A new technique for studying extended defects and dislocation networks is proposed. The approach, based upon the continuum theory of crystal defects, is employed for digital image processing of high-resolution transmission electron micrographs. The procedure starts ...
CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown usi... more CdTe nanowires with the average diameter of only 40 nm coated with (Cd,Mg)Te shells are grown using Au-catalyzed vapor-liquid-solid growth mechanism in a system for molecular beam epitaxy. High optical quality of individual nanowires is revealed by means of low temperature cathodoluminescence and micro-luminescence. It is found that, the optical emission spectrum consists mostly of the near band edge emission without any significant contribution of defect related luminescence. Moreover, the importance of surface passivation with (Cd,Mg)Te coating shells is demonstrated.
The effect of Cu ion doping on the photoluminescence (PL) and magnetic behavior of ZnO/MgO and Zn... more The effect of Cu ion doping on the photoluminescence (PL) and magnetic behavior of ZnO/MgO and ZnO/oleic acid core/shell nanoparticles is investigated.
We report on Au catalyst-assisted molecular beam epitaxy growth and properties of pure ZnSe and Z... more We report on Au catalyst-assisted molecular beam epitaxy growth and properties of pure ZnSe and ZnSe/CdSe superlattice nanowires. In particular, we concentrate our attention on the morphological characterization by transmission and scanning electron microscopy of pure ZnSe NWs and we compare their optical properties with those of ZnSe/CdSe superlattice NWs fabricated at the same technological conditions.
ZnTe nanowires produced by molecular beam epitaxy via the vapour/liquid/solid mechanism were stud... more ZnTe nanowires produced by molecular beam epitaxy via the vapour/liquid/solid mechanism were studied by transmission electron microscopy. The wires grew along the ?111? directions pointing out of the (001)-oriented GaAs substrate. The length of the wires amounted to some microns depending on the growth time. The mean diameter ranged between 30 and 60 nm depending on the size of the
ABSTRACT MBE grown ZnTe/CdxZn1-xTe superlattices containing a high density of quantum dots have b... more ABSTRACT MBE grown ZnTe/CdxZn1-xTe superlattices containing a high density of quantum dots have been investigated by quantitative TEM methods. The Cd concentration in the superlattice was determined from local lattice parameter measured by digital processing of experimental HRTEM images. For the 15ML(ZnTe)/2ML(CdTe) superlattice, the density of quantum dots is 1.3x106 P-3. The dots are Cd rich islands of diameter from 6 to 8 nm and hights below 1.5 nm. The Cd concentration in islands centre was estimated to be between x=0.35 and x=0.85. Areas with ordering of QD were observed.
An arrangement of self-assembled GaN nanowires (NWs) grown by plasma-assisted molecular beam epit... more An arrangement of self-assembled GaN nanowires (NWs) grown by plasma-assisted molecular beam epitaxy on a Si(111) substrate is studied as a function of the temperature at which the substrate is nitridized before GaN growth. We show that the NWs grow with the c-axis perpendicular to the substrate surface independently of nitridation temperature with only a slight improvement in tilt coherency for high nitridation temperatures. A much larger influence of the substrate nitridation process on the in-plane arrangement of NWs is found. For high (850 °C) and medium (450 °C) nitridation temperatures angular twist distributions are relatively narrow and NWs are epitaxially aligned to the substrate in the same way as commonly observed in GaN on Si(111) planar layers with an AlN buffer. However, if the substrate is nitridized at low temperature (~150 °C) the epitaxial relationship with the substrate is lost and an almost random in-plane orientation of GaN NWs is observed. These results are correlated with a microstructure of silicon nitride film created on the substrate as the result of the nitridation procedure.
The structure of GaMnAs nanowires (NW) with nominal Mn concentration of up to 7 at% was investiga... more The structure of GaMnAs nanowires (NW) with nominal Mn concentration of up to 7 at% was investigated by transmission electron microscopy. The (Ga,Mn)As NW were grown on epiready GaAs(001) n-type wafers by molecular beam epitaxy. The crystal structure of the NW was determined to be zinc-blende. NW with Mn concentrations lower than 5 at% grow along the 111 direction. NW with higher Mn concentrations grow along the 110 direction and reveal a branching structure. The main nanowire and branches grow along the 110 directions belonging to only one {111} plane.
Uploads
Papers by S. Kret