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Ar–O–Zn plasma discharges created during DC reactive magnetron sputtering of a Zn target and RF reactive magnetron sputtering of a ceramic ZnO target were investigated and compared by means of the Langmuir probe measurements in order to determine the mechanism of growth of porous Zn films during DC-mode Zn reactive sputtering. The power supplied to the magnetrons during the sputtering was kept at 125 W and the plasma was characterised as a function of oxygen content in the sputtering gas mixture, ranging from 0 to 60% for two gas pressures related to porous Zn film deposition, namely 3 mTorr and 5 mTorr. Based on the correlation of plasma properties measurements with scanning electron microscope imaging and X-ray diffraction of the films deposited under selected conditions it was found that the growth of porous, polycrystalline Zn films was governed by high electron density in the plasma combined with a high electron temperature and an increased energy of the ions impinging on the substrate. [ABSTRACT FROM AUTHOR]

Granular GaAs(MnAs) layers with different Mn concentration and various layer thickness were grown by MBE method and subjected to annealing at 500°C under ambient and enhanced hydrostatic pressure. Distinct influence of hydrostatic pressure applied during annealing on strain state of layers as well as on hexagonal MnAs inclusions was found. Pressure induced strain of inclusions is related to different bulk moduli of GaAs and of hexagonal MnAs. Formation of hexagonal inclusions depends on concentration of Mn in interstitial position in as-grown samples. [ABSTRACT FROM AUTHOR]

Abstract: Advanced electronic devices based on III-N semiconductors, particularly these operated at the high power and high frequency or corrosive atmosphere, need elaboration of new technology for contacts metallization which are thermally and chemically stable. Performed studies aimed at the development of materials for applications in the improved metallization. Due to the unique combination of the metallic electro-thermal conductivity and ceramic resistance to oxidation and thermal stability, the MAX phases were chosen as the materials potentially applicable to this task. Particular interest lies in the MAX phases based on the Ti, Si and C or N atoms, especially on the Ti3SiC2 phase. The paper focuses on a comprehensive characterization of films grown by means of high-temperature magnetron Ti, Si and C co-sputtering. The complementary characterization by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) is presented. XRD studies pointed out the presence of several phases in the investigated samples, therefore XAS as an atomic sensitive probe was applied to examine the average atomic order around Ti atoms as a function of the technological parameters and to point towards proper procedures to achieve the appropriate stoichiometry around Ti atoms and finally the Ti3SiC2 phase. [Copyright &y& Elsevier]

Abstract: The magnetic properties of a Cd1−x Mn x GeAs2: MnAs hybrid micro-composite have the signature of ferromagnetic order at room temperature. Magnetotransport reveals the presence of a large linear positive magnetoresistance, with maximum values of about 550% ( T) for . This is interpreted in terms of an effective medium approximation with the value and the shape of the magnetoresistance depending on the structural and electronic properties of the semiconductor rather than on its magnetic properties. The absence of an anomalous Hall effect leads to the conclusion that ferromagnetic ordering is not the only factor necessary for the occurrence of asymmetric scattering in granular ferromagnetic materials. [Copyright &y& Elsevier]

Abstract: Structural and magnetic properties of GaAs thin films with embedded nanoclusters were investigated as a function of the annealing temperature and Mn content. Surprisingly, the presence of two kinds of nanoclusters with different structure was detected in most of the samples independently of the thermal processing or Mn content. This proved that the presence of a given type of clusters cannot be assumed a priori as is reported in many papers. The fraction of Mn atoms in each kind of cluster was estimated from the extended X-ray absorption fine structure analysis. This analysis ruled out the possibility of the existence of nanoclusters containing a hypothetic MnAs cubic compound—only (Ga,Mn)As cubic and hexagonal MnAs clusters were detected. Moreover the bimodal distribution of Mn magnetic moments was found, which scales with the estimated fraction of Mn atoms in the cubic and hexagonal clusters. [Copyright &y& Elsevier]

We report on the first studies of the optical properties of MBE-grown ZnTe nanowires (NWs). The growth of ZnTe NWs was based on the Au-catalyzed vapour-liquid-solid mechanism and was performed on (001), (011), or (111)B-oriented GaAs substrates. Investigated NWs have a zinc-blende structure, the average diameter of about 30 nm, and typical length between I and 2 µm. Their growth axes are oriented along <111>-type directions of the substrate. The structural characterization of the NWs was performed by means of X-ray diffraction, using the synchrotron radiation corresponding to the wavelength of CuKα1 radiation W I beamline at Hasylab DESY). The macro-Raman spectra of either as-grown NWs on GaAs substrate or of NWs removed from substrate and deposited onto Si were collected at temperatures from 15 K to 295 K using Ar+ and Kr+ laser lines. Strong enhancement of ZnTe-related LO-phonon structure was found for an excitation close to the exciton energy. Our studies revealed also the presence of small trigonal Te precipitates, typical of tellurium compounds. [ABSTRACT FROM AUTHOR]

Abstract: The crystalline structure and surface morphology of Dy x O y dielectric films grown on Si substrates were studied by grazing incidence diffraction and absorption with use of synchrotron radiation and by atomic force microscopy. The crystalline structure and the roughness of Dy x O y films were found to be strongly dependent on the deposition rate. The dielectric-silicon interface depends on the type of gas used in the annealing process. Moreover, results from the near edge X-ray absorption studies, have revealed that none of the examined films has a stoichiometry close to the Dy2O3. The level of stoichiometry is determined by the technological conditions. Nevertheless, MOS structures with Dy x O y films (EOT∼23Å) have shown a rather good Dy x O y -Si interface properties, which can be further improve by thermal annealing, and introducing of several additives, therefore Dy x O y films can be considered as suitable candidates for gate dielectric in MOS devices. [Copyright &y& Elsevier]

Cr-based diluted magnetic semiconductors (DMSs) have attracted a lot of attention within the last few years because of their possible applications in the area of spintronics. Modern growth techniques of such materials require efficient methods of characterization of their structure. In this work, the structure of Cr-rich ZnSe layers grown by MBE on (0 0 1) GaAs substrate was investigated by means of the high-resolution X-ray diffraction, atomic force microscopy and Raman scattering. Direct evidence of the mixed Zn1-xCrxSe crystal in the zinc-blende phase is demonstrated by the high resolution X-ray diffraction (a part of Cr is shown to occupy the cationic sites in the crystal lattice). The presence of amorphous or crystalline Se- and Cr-related precipitates in selected samples is demonstrated, their influence on the properties of (Zn,Cr)Se layers is discussed. [Copyright &y& Elsevier]

High-pressure diffraction experiments for wurtzite-type zinc magnesium selenide were performed using a large-anvil X-ray diffraction press, MAX80, and synchrotron radiation. The pressure dependence of unit-cell parameters was determined for Zn0.53Mg0.47Se for pressures ranging up to 5.17 GPa. The value of bulk modulus and its pressure derivative were calculated from the pressure–volume dependence by fitting the Birch–Murnaghan equation of state (EOS). They are compared with reported data for ZnSe, MgSe and some related solid solutions. Photoluminescence (PL) data for Zn0.38Mg0.62Se were collected using a diamond-anvil cell at a lower pressure. These data show an evolution of the main deep-levels emission band: a narrowing of the spectrum, an increase of luminescence intensity and a blue shift. [Copyright &y& Elsevier]

In-Ga-Zn-O thin films were fabricated by means of reactive RF magnetron sputtering. Mechanism of free electrons generation via oxygen vacancies formation is proposed to determine the relationship between oxygen content in the deposition atmosphere and the transport properties of IGZO thin films. The depletion-mode a-IGZO thin film transistor with field-effect mobility of 12 cm2/(V s) has been demonstrated. [ABSTRACT FROM AUTHOR]

Positron annihilation spectroscopy is used to study point defects in Zn1-xMnxGeAs2 crystals with low Mn content 0 ≤ χ ≤ 0:042 with disordered zincblende and chalcopyrite structure. The role of negatively charged vacancies and non-open-volume defects is discussed with respect to the high p-type conductivity with carrier concentration 1019 ≤ p ≤ 1021 cm-3 in our samples. Neutral As vacancies, together with negatively charged Zn vacancies and non-open-volume defects with concentrations around 1016 - 1018 cm-3, are observed to increase with increasing Mn content in the alloy. The observed concentrations of defects are not sufficient to be responsible for the strong p-type conductivity of our crystals. Therefore, we suggest that other types of defects, such as extended defects, have a strong influence on the conductivity of Zn1-xMnxGeAs2 crystals. [ABSTRACT FROM AUTHOR]

We present systematic studies of magnetic and transport properties of Zn1-xMnxGeAs2 semimagnetic semiconductor with the chemical composition varying between 0.053≤x≤0.182. The transport characterization showed that all investigated samples had p-type conductivity strongly depending on the chemical composition of the alloy. The Hall effect measurements revealed carrier concentrations p≥1019 cm-3 and relatively low mobilities, μ≤15 cm2/(V s), also chemical composition dependent. The magnetic investigations showed the presence of paramagnet-ferromagnet phase transitions with transition temperatures greater than 300 K for the samples with x≥0.078. We prove by means of x-ray diffraction, nuclear magnetic resonance, and scanning electron microscopy techniques that the observed room temperature ferromagnetism is due to the presence of MnAs inclusions. The high field magnetoresistance showed the presence of giant magnetoresistance effect with maximum amplitudes around 50% due to the presence of nanosize ferromagnetic grains. [ABSTRACT FROM AUTHOR]

In this work, the Si+ doping of undoped GaN (n ∼1 × 1016 cm−3) on sapphire by a single step implantation or sequential implantation/recrystallization processes, to a total fluence of 1 × 1016 at/cm2 and subsequent activation annealing at 1100 °C for 2 min, were demonstrated and analysed. We proved that the multicycle implantation/recrystallization process is better in terms of structural and electrical parameters of implanted region than conventional single step implantation. Rutherford backscattering spectrometry in channeling geometry (RBS/c), McChasy simulations and atomic force microscopy (AFM) studies showed, that the proposed process does not deteriorate surface morphoplogy and leads to a significantly lower defect concentrations. Low resistivity ohmic contacts, with R C < 0.1 Ω mm, to low sheet resistivity Si-implanted GaN region (R SH = (36.9 ± 0.7) Ω/sq.), were obtained with the use of sequential implantation with 30 s recrystallization annealing. [ABSTRACT FROM AUTHOR]

We have studied the structural mechanisms responsible for the magnetic reorientation between in-plane and out-of-plane magnetization in the (25 nm Pt)/(3 and 10 nm Co)/(3 nm Pt) trilayer systems irradiated with nanosecond XUV pulses generated with laser-driven gas-puff target plasma source of a narrow continuous spectrum peaked at wavelength of 11 nm. The thickness of individual layers, their density, chemical composition and irradiation-induced lateral strain were deduced from symmetric and asymmetric X-ray diffraction (XRD) patterns, grazing-incidence X-ray reflectometry (GIXR), grazing incidence X-ray fluorescence (GIXRF), extended X-ray absorption fine structure (EXAFS) and transmission electron microscopy (TEM) measurements. In the as grown samples we found, that the Pt buffer layers are relaxed and that the layer interfaces are sharp. As a result of a quasi-uniform irradiation of the samples, the XRD, EXAFS, GIXR and GIXRF data reveal the formation of two distinct layers composed of Pt 1-x Co x alloys with different Co concentrations, dependent on the thickness of the as grown magnetic Co film but with similar ∼1% lateral tensile residual strain. For smaller exposure dose (lower number of accumulated pulses) only partial interdiffusion at the interfaces takes place with the formation of a tri-layer composed of Co-Pt alloy sandwiched between thinned Pt layers, as revealed by TEM. The structural modifications are accompanied by magnetization changes, evidenced by means of magneto-optical microscopy. The difference in magnetic properties of the irradiated samples can be related to their modification in Pt 1-x Co x alloy composition, as the other parameters (lateral strain and alloy thickness) remain almost unchanged. The out-of-plane magnetization observed for the sample with initially 3 nm Co layer can be due to a significant reduction of demagnetization factor resulting from a lower Co concentration. [ABSTRACT FROM AUTHOR]

In this paper we report on the analysis of Al+-implanted ZnO/GaN bilayers in search for the damage production mechanism and possible ion mixing. 100 nm or 200 nm thick ZnO epitaxial layers were grown on GaN substrates by either sputter deposition or atomic layer deposition technique followed by adequate annealing. Ion irradiations of ZnO/GaN were carried out at room temperature using 200 keV Al+ ions with fluences of 2 x 1015 and 1016 at./cm². Unprocessed and irradiated samples were characterized by the Rutherford backscattering spectrometry in channeling geometry (RBS\c), X-ray diffraction and transmission electron microscopy. Additionally, secondary ion mass spectrometry was employed for the aforementioned samples as well as for the implanted samples subjected to further annealing. It was found that the damage distributions in ZnO/GaN differ considerably from the corresponding defect profiles in the bulk ZnO and GaN crystals, most probably due to an additional strain originating from the lattice mismatch. Amount of intermixing appears to be relatively small; apparently, efficient recombination prevents foreign atoms to relocate to large distances. [ABSTRACT FROM AUTHOR]

[Display omitted] • Quasi-ternary ZnO/MgO alloys are grown by MBE as an alternative to random alloys. • The highest mean Mg concentration is reaching 72%. • Critical thickness of Mg layers for retaining wurtzite crystallinity is established. • HAADF images confirmed thicknesses of ZnO and MgO layers assessed with two approaches of simulation of XRD diffractograms. • Biaxial strains at interfaces are partly responsible for creation of ZnMgO region, which influences WZ structure retainment. The analysis of heteroepitaxially grown ZnO/MgO superlattices on a -oriented ZnO substrates was described. The influence of unalike natural crystalline structures of ZnO and MgO on the interface's abruptness and retaining wurtzite crystallinity was studied. Wurtzite structure was found to be retained in the MgO thin barriers up to 1.5 nm, but creation of nonuniform biaxial strains and some interdiffusion of Mg from barriers to ZnO QW's seemed to be inevitable. The complex strain/composition heterogeneities can be explained by the difference of vapor pressure between Mg (p = 1.93 Pa) and Zn (p = 0.22 Pa) elements at growth temperatures and high mobility of Mg atoms, which are gladly incorporated into ZnO matrix. As a result, a subtle three monolayers in size ZnMgO film was created at the interfaces, which was partly responsible for retaining the wurtzite structure of coherently grown MgO layers. [ABSTRACT FROM AUTHOR]

Abstract: Silicon single crystals were implanted with 160keV Mn+ ions to a dose of 1×1016 cm−2 and next annealed for 1h up to 1070K under ambient pressure. Glancing incidence diffraction research performed using synchrotron radiation indicated that the post-implantation treatment influenced the creation of Mn4Si7 nanoinclusions. The dimensions and concentration of these inclusions, calculated from distribution of the X-ray diffuse scattering intensity are dependent on annealing temperature. The sizes and shapes of the inclusions were also determined by high-resolution transmission electron microscopy. Magnetic properties of the Si:Mn samples were studied using superconducting quantum interference device. The origin of ferromagnetic ordering is discussed in terms of the size of nanoinclusions. [Copyright &y& Elsevier]

Abstract: Optical properties of p-type Zn1− x Mn x GeAs2 for 0⩽ x ⩽0.078 were investigated by Raman spectroscopy at room temperature. Phonons of ZnGeAs2 are experimentally determined and they are in excellent agreement with those theoretically predicted. Existence of MnAs clusters was confirmed in the sample with the highest concentration of Mn. MnAs was found in α and β phases and their vibrational frequencies are obtained experimentally. Plasmon – two different phonons interaction in Zn1− x Mn x GeAs2 is registered and analyzed. [Copyright &y& Elsevier]

Abstract: Effect of processing of Si:Mn at up to 1270K (HT) under enhanced hydrostatic pressure (HP, up to 1.1GPa) for 1h on its microstructure has been investigated by X-ray and SIMS methods. Si:Mn was prepared by implantation at 610K of Mn+ ions (dose 1×1016 cm−2, energy 160keV) into (001) oriented Czochralski (Cz-Si) or Floating zone (Fz-Si) silicon with interstitial oxygen concentration, c o =1.5×1017 cm−3 (Fz-Si) or 9×1017 cm−3 (Cz-Si). The defect structure of Si:Mn depends on c o, HT and HP. The intensity of X-ray diffraction peaks originating from the ferromagnetic Mn4Si7 phase (with the lattice parameters a =0.5525nm and c =1.7463nm) increases with HT, up to 1070K. Markedly shifted Mn atom concentration towards the surface is observed after processing of Si:Mn at ≥1000K, especially under 105 Pa. Processing at 1270K results in the decreased content of Mn4Si7; Mn diffusivity decreases with HP. Oxygen gettering within the implantation-disturbed area has been stated. [Copyright &y& Elsevier]

Abstract: Au films of thickness ranging between 5 and 52nm were prepared by sputtering on quartz substrates and their third-order nonlinear optical response was investigated by Optical Kerr effect (OKE) and Z-scan techniques using 532nm, 35ps laser pulses. All prepared films were characterized by XRD, AFM and UV–VIS–NIR spectrophotometry while their third-order susceptibility χ (3) was measured and found to be of the order of 10−9 esu. The real and imaginary parts of the third-order susceptibility were found in very good agreement with experimental results and theoretical predictions reported by Smith et al. [D.D. Smith, Y. Yoon, R.W. Boyd, Y.K. Cambell, L.A. Baker, R.M. Crooks, M. George, J. Appl. Phys. 86 (1999) 6200]. [Copyright &y& Elsevier]

Abstract: We report on the fabrication of thin ZnO:N film by thermal oxidation of zinc nitride layers sputter-deposited on quartz, sapphire, GaN, and ZnO surfaces. Through optimising several crucial technological steps we have achieved p-type conductivity with the carrier concentration in mid 1017 cm−3 range and mobility of ∼10cm2/Vs. Rich photoluminescence spectra have been observed in the region corresponding to the fundamental energy gap region with peaks that can be related to acceptor bound exciton transitions. The transmittance of p-ZnO:N in the whole visible spectrum is ∼80%. [Copyright &y& Elsevier]

We report on the growth of monocrystalline thin films of ZnSe and ZnO by atomic layer epitaxy by simple reaction between elemental precursors. Structural and optical properties of these films are discussed with reference to the investigations performed with atomic force microscopy, scanning electron microscopy, cathodoluminescence and photoluminescence. [Copyright &y& Elsevier]

Heteroepitaxial growth of multilayer thin films of Nd0.67Sr0.33MnO3/YBa2Cu3O7 (NSMO/YBCO) by high-pressure sputtering is reported. We found that critical thickness of YBCO layers for the occurrence of superconductivity in multilayered structure is 3 unit cell. The onset of the temperature of diamagnetic response is lower than the zero resistance superconducting transition temperature. Magnetic hysteresis loops show the coexistence of superconductivity and ferromagnetic order at nm length scale. [Copyright &y& Elsevier]

We discuss light emission properties from thin films of ZnSe grown by atomic layer epitaxy on GaAs (1 0 0). White color emission is observed in photoluminescence and cathodoluminescence, due to the observation of three RGB emission bands. We demonstrate possibility of color tuning by either variation of film thickness or, in cathodoluminescence experiments, variation of an accelerating voltage. [Copyright &y& Elsevier]

The exchange interaction between band carriers and localized magnetic moments was studied in MBE grown zinc blende Mg1−xMnxTe epilayers. Magnetic circular dichroism and magnetization were measured as a function of magnetic field at low temperature. The obtained exchange parameter (N0α−N0β) is lower than in Cd1−xMnxTe and Zn1−xMnxTe. Possible mechanisms leading to weaker s,p–d exchange interaction in Mg1−xMnxTe are discussed. [Copyright &y& Elsevier]

The basic structural and detailed analysis of the optical properties of homoepitaxially grown ZnO/MgO superlattices (SLs) on a-oriented ZnO substrates, containing 30 periods of layers, was described. We found using Rutherford backscattering spectroscopy that the wurtzite coordination collapses in the SLs with 3 nm MgO thick barriers. This novel information allows taking this value as the limit for the maximum MgO barrier thickness in such structures. The observed luminescence and the performed calculations of excitonic transitions suggest that such a high energy barrier of MgO allows treating the ZnO layers in these SLs as separate, non-interacting quantum wells. Cross-sectional SEM-CL line scans revealed MgO layer thickness-dependent biaxial strains built up in the QWs structures. [Display omitted] • Quasi-ternary ZnO/MgO alloys are grown by MBE as an alternative for random alloys. • The highest mean Mg concentration is reaching 72%. • Critical thickness of Mg layers for retaining wurtzite crystallinity is established. • Theoretical calculations confirm observed PL emission and deliver confirmation of ZnO QWs layers thicknesses. • CS-CL line scans revealed a ZnO D0X line blue shift in the SL, pointing to MgO thickness dependent biaxial strains build-up. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of low-energy rhenium implanted c-Si are examined for the first time. The damage created by rhenium ions and the following partial reconstruction of the silicon host matrix after rapid thermal annealing (RTA) are investigated as a function of the fluence. Rutherford backscattering spectrometry (RBS) results reveal that the implanted ions are located in the near-surface region with the distribution maximum at about 23 nm below the surface. The analysis of rhenium-depth distribution using the McChasy code shows that the implanted Re-ions are located in the interstitial lattice positions. The RTA leads to a partial recovery of the silicon crystal structure. According to the RBS results, the formed inclusions are not coherent with the silicon host matrix causing an increase of the lattice distortion. Analysis of channeled RBS/c spectra carried out by the McChasy code revealed different levels of bent channels in damaged regions suggesting bimodal distribution of inclusions in the silicon. Studies of high-resolution X-ray photoelectron spectroscopy (XPS) conducted after the RTA showed the shift of Re 4 f 7/2 binding energy (BE) by +0.68 and + 0.85 eV with respect to metallic rhenium for the samples with lower/higher fluencies, respectively. Complex XPS, density functional theory (DFT) simulations, and transmission electron microscopy (TEM) data analysis allowed us to conclude that the near-surface layer of the sample (∼10 nm) consists of nanoinclusions with cubic and/or hexagonal ReSi. In the middle area of the samples, much larger nanoinclusions (>10/20 nm for higher/lower fluencies, respectively) containing pure metallic rhenium inside are formed. The RTA increases the magnetic moment of the sample with the lower dose nearly 20-fold, whereas in the sample with the higher dose a 3-fold increment is observed only. The magnetic response of the examined systems after the RTA indicates a presence of magnetic interactions between the nanoinclusions resulting in the system exhibiting super-spin glass or super-ferromagnetism. Image 1 • The structural, electronic, and magnetic properties of low-energy rhenium implanted c-Si are examined for the first time. • The implanted Re-ions are located in the interstitial lattice positions in the silicon matrix. • Complex XPS, DFT simulations, and TEM data analysis conclude that nanoinclusions are cubic and/or hexagonal ReSi. • Analysis of rhenium-depth distribution and channeled RBS spectra suggests bimodal distribution of inclusions in the silicon. • Magnetic interactions between the nanoinclusions exists resulting in super-spin glass or super-ferromagnetism. [ABSTRACT FROM AUTHOR]

We present the studies of structural, magnetic, and magnetotransport properties of Cd1-x-y Mnx Zny SnAs2 crystals with the average Mn contents x changing from 0.013 to 0.170 and Zn contents y varying from 0.002 to 0.051. Homogenous distribution of Mn ions is observed for the samples with x = 0.025. The presence of Mn As clusters in the studied alloy for x > 0.025 induces room-temperature ferromagnetism with the Curie temperature TC, with values around 325K. High crystal quality leads to high carrier mobility values observed for all of our samples, as high as 7100 cm²/(Vs) for x = 0.025 and y = 0.028. The Shubnikov-de Haas oscillations are observed at T = 50 K for all of our samples. The oscillations allowed the calculation of the effective mass m*, giving values of about 0.11-0.12me. The presence of magnetic impurities has a strong influence on the magnetoresistance of the alloy. For the samples with x = 0.076, the Shubnikov-de Haas oscillations are observed on the background of a strong linear positive magnetoresistance, present up to room temperature. The maximum values of the linear positive magnetoresistance are close to 200% for the sample with x = 0.170 and y = 0.002, at T = 1.5K. This positive magnetoresistance is related to the presence of Mn As clusters in the semiconductor lattice. [ABSTRACT FROM AUTHOR]

Abstract: GaMnAs layers on (001)-oriented GaAs substrates were grown by the molecular beam epitaxy (MBE) method. Structural properties of samples processed at up to 920K under hydrostatic Ar pressure up to 1.1GPa were investigated by X-ray, secondary ion mass spectroscopy and atomic force microscopy methods. The sign of strain (compressive or tensile) of the GaMnAs layers, related to a creation of MnAs nanoclusters, is found to be dependent on processing conditions and on primary structure defects, whereas it was independent of Mn concentration. An influence of the defects structure in as-grown samples on the strain state of processed GaMnAs layers is discussed. [Copyright &y& Elsevier]

Modifications of magnetic and magneto-optical properties of Pt/Co(d Co )/Pt upon Ar + irradiation (with energy 1.2, 5 and 30 keV) and fluence, F at the range from 2 · 10 13 -2 · 10 16 Ar + cm -2 ) were studied. Two 'branches' of increased perpendicular magnetic anisotropy (PMA) and enhanced magneto-optical response are found on 2D (d Co , F) diagrams. The difference in F between 'branches' is driven by ion energy. Structural features correlated with magnetic properties have been analysed thoroughly by x-ray diffraction, Rutherford backscattering spectrometry and positron annihilation spectroscopy. Experimental results are in agreement with TRIDYN numerical calculations of irradiation-induced layers intermixing. Our work discusses particularly structural factors related to crystal lattice defects and strain, created and modified by irradiation, co-responsible for the increase in the PMA.

We present studies of structural, magnetic, and electrical properties of Zn1-x Mn x SnSb2+MnSb nanocomposite ferromagnetic semiconductors with the average Mn-content, [Formula: see text], changing from 0.027 up to 0.138. The magnetic force microscope imaging done at room temperature shows the presence of a strong signal coming from MnSb clusters. Magnetic properties show the paramagnet-ferromagnet transition with the Curie temperature, T C, equal to about 522 K and the cluster-glass behavior with the transition temperature, T CG, equal to about 465 K, both related to MnSb clusters. The magnetotransport studies show that all investigated samples are p-type semiconductors with high hole concentration, p, changing from 10(21) to 10(22) cm(-3). A large increase in the resistivity as a function of the magnetic field is observed at T  <  10 K and small magnetic fields, [Formula: see text] mT, for all the studied samples with a maximum amplitude of the magnetoresistance about 460% at T  =  1.4 K. The large increase in the resistivity is most probably caused by the appearance of the superconducting state in the samples at T  <  4.3 K.

An enhancement of the Zeeman splitting as a result of the incorporation of paramagnetic Mn ions in ZnMnTe/ZnMgTe core/shell nanowires is reported. The studied structures are grown by gold-catalyst assisted molecular beam epitaxy. The near band edge emission of these structures, conspicuously absent in the case of uncoated ZnMnTe nanowires, is activated by the presence of ZnMgTe coating. Giant Zeeman splitting of this emission is studied in ensembles of nanowires with various average Mn concentrations of the order of a few percent, as well as in individual nanowires. Thus, we show convincingly that a strong spin sp-d coupling is indeed present in these structures.

ZnTe-ZnO core-shell radial heterostructures were grown using a new method of combining molecular beam epitaxy (MBE) and atomic layer deposition (ALD). Zinc telluride nanowires (core) were grown on a GaAs substrate using gold catalyzed vapor-liquid-solid mechanism. An atomic layer deposition technique using diethyl zinc and deionized water as precursors was applied for zinc oxide shell formation. The core-shell ZnTe-ZnO heterostructures thus obtained were characterized by scanning electron microscopy, transmission electron microscopy, x-ray diffraction and photoluminescence measurements.

It is shown that the growth of II-VI diluted magnetic semiconductor nanowires is possible by the catalytically enhanced molecular beam epitaxy (MBE). Zn(1-x)MnxTe NWs with manganese content up to x=0.60 were produced by this method. X-ray diffraction, Raman spectroscopy, and temperature dependent photoluminescence measurements confirm the incorporation of Mn(2+) ions in the cation substitutional sites of the ZnTe matrix of the NWs.

This paper reports on the epitaxial growth of single-crystalline ternary Zn(1-x)Mg(x)Te nanowires covering a broad compositional range of molar fraction 0≤x≤0.75. The nanowires were grown on (100), (110), and (111) GaAs substrates using a vapor-liquid-solid mechanism. Solid source molecular beam epitaxy and an Au-based nanocatalyst were used for these purposes. The composition of nanowires can be adjusted by changing the ratio of Mg to Zn molecular beam fluxes. Electron microscopy images show that the nanowires are smooth and slightly tapered. The diameters of the obtained nanowires are from 30 to 70 nm and their length is around 1 µm. X-ray diffraction analysis and transmission electron microscopy reveal that the nanowires have a zinc-blende structure throughout the whole range of obtained compositions, and have a [Formula: see text] growth axis. The Raman measurements reveal both the expected splitting and shift of phonon lines with increasing Mg content, thus proving the substitutional incorporation of Mg into metallic sites of the ZnTe lattice.