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Understanding how Sb atoms are located in the ZnO crystal lattice and how they affect the layer parameters is essential to obtain p-type conductivity in ZnO:Sb. In this paper, the results of our extensive research (XPS, Raman, X-Ray, SIMS) of Sb doped ZnO films grown by Molecular Beam Epitaxy are presented. It is shown with use of high resolution X-ray Photoemission Spectroscopy (XPS) that three charge states of the Sb impurity: Sb3+, Sb5+, and Sb3− can exist in ZnO:Sb layers. The dominant charge state of Sb ions is 3 + while the contribution of 5 + is very low. The relative fraction of Sb atoms located at the Zn sites is about ∼90%, while ∼10% are incorporated in oxygen sites. It was found that increasing the Sb content in the layers increases the intensity of Raman modes at 511 cm−1, 533 cm−1, and 575 cm−1, which confirms their correlation with Sb doping. Additionally, a blue shift of the E2High Raman mode of ZnO was observed, related to the increase of strain in the oxygen sublattice. The relation between strain and stress for different Sb chemical states (Sb3+, Sb5+, Sb3−) in ZnO is calculated and compared with experimental results.

In this paper the current understanding of defects in acceptor doped ZnO is briefly reviewed. The results of investigations of ZnO:As/n-GaN heterojunctions which have been successfully fabricated by plasma assisted molecular beam epitaxy method are presented. The electrical properties of the junctions, as well as deep levels, have been studied by means of current-voltage (I-V), capacitance-voltage (C-V) characteristics and deep level transient spectroscopy (DLTS). Electrical measurements were supplemented by photoluminescence- (PL) along with secondary ion mass spectrometry (SIMS) and X-ray photoemission spectroscopy (XPS) investigations. The I-V measurements allowed for detailed analysis of current mechanisms, through which the presence of trap states in the investigated junction was confirmed. The C-V results proved that the depletion region of the diode is located within the ZnO:As layer. The DLTS measurements revealed the presence of three hole trap related signals. The activation energies and capture cross sections of these traps were determined and their possible origin has been ascribed. Obtained results allowed for better identification of defects found in the case of the analyzed heterostructure, as well as the studies of its electronic properties.

Zinc oxide films single, double and triple doped with arsenic, arsenic and nitrogen, arsenic, nitrogen and antimony, were grown by plasma assisted molecular beam epitaxy. Differently doped ZnO samples were post-growth annealed in oxygen or argon atmospheres. Incorporation of impurities into ZnO layers was confirmed by the results of secondary ion mass spectrometry measurements. The high resolution X-ray photoelectron spectroscopy (XPS) studies of arsenic 3d state revealed three arsenic states at the binding energy of ∼41 eV, 44.2 and 45.6 eV which we attribute to As deep acceptor, As Zn -2V Zn shallow acceptor, and to As Zn donor, respectively. Concentration of the As O species was found to be low in all samples. The relative fractions of arsenic chemical states in As-doped ZnO layers, were altered as a result of doping by antimony and/or nitrogen and post grown annealing in argon and oxygen atmosphere.

Structural properties, magnetization and magnetocaloric effect measurements in the compounds based on lanthanum–strontium–bismuth manganites La 0.7 Sr 0.3 − x Bi x MnO 3 (LSBiMO) with 0.05 ⩽ x ⩽ 0.30 have been performed. The valence states of elements entering into the composition of investigated LSBiMO samples were analyzed for x = 0.15 and 0.3 using the HR XPS spectra of Bi 4f, La 3d, Mn 3s and Sr 3d. According to X-ray powder diffraction data the crystalline structure of the samples is perovskite-like with a small rhombohedral distortion. The a and c lattice parameters and unit cell volume V are established to increase with increasing Bi content. All the manganites show ferromagnetic-like ordering with second order phase transition to paramagnetic state. The Curie temperature and magnetization decrease at substitution of Sr 2+ for Bi 3+ ions. The magnetic entropy changes were calculated using the field dependence of isothermal magnetization in the terms of the thermodynamic Maxwell relation. The maximum magnetic entropy change value was shown to be 0.94 J kg −1 K −1 for x = 0.05 for a field change of 1 T.

The XPS technique combined with low energy Ar + ion sputter depth profiling was used to obtain information about chemical composition and reproducibility of the growth procedure by the MOVPE method of the InGaN multi quantum wells (MQWs). A good in-depth resolution of the XPS depth profiling technique, allows observation of InGaN quantum wells with thickness down to 2 nm. However quantitative characterization of very narrow QWs is limited by the elemental detection range of the XPS analysis. Both the InGaN QWs and GaN barriers parameters were well characterized using the model MQWs samples with various QW thickness. Inter-diffusion of indium within the GaN barrier layers, induced by high-temperature annealing, has been detected. This work evidences the successful application of the XPS depth profiling analysis as a very useful tool to optimize the growth parameters and thermal stability of InGaN/GaN MQWs.

Electron transport in both ZnO(0 0 0 1)–Zn and ZnO(0 0 0–1)–O bulk single crystals was studied using the elastic-peak electron spectroscopy (EPES) measurements. The inelastic mean free path (IMFP) was evaluated from EPES using both Ni and Au standards in the energy range 200–2000 eV, and compared with IMFPs calculated from the predictive TPP-2 M formula for the measured composition of both single crystal surfaces. In the electron energy range from 1 to 2 keV, the IMFPs were found to be 34% larger for the ZnO(0 0 0 1)–Zn crystal surface than for the ZnO(0 0 0–1)–O crystal surface, and considerably larger than the IMFPs obtained from the TPP-2 M predictive formula. At energies lower than 1 keV, a good agreement between the corresponding IMFPs values was found. However, the electron transport at larger energies seems to be affected by different bulk structure of both crystals.

Arsenic-doped ZnO films were formed by thermal annealing of epitaxial ZnO films grown by Atomic Layer Deposition (ALD) in arsenic atmosphere at temperature 850–950 °C. X-ray photoelectron spectroscopy (XPS) studies of the ZnO:As films revealed the complex As3d core level spectra formed by three components located at about 41 eV, 45 eV and 47.5 eV below the Fermi level. The As3d component at binding energy (BE) of 45 eV was found to be correlated with the acceptor bound A°X exciton state observed in low temperature photoluminescence. This observation strongly supports the previously postulated assumption that the origin of the 45 eV component of the As3d spectra can be ascribed to arsenic atoms in As Zn –2V Zn complexes formed as a result of high temperature annealing. This assumption is also supported by the evident valence band shift towards the Fermi level in the ZnO:As film annealed at 950 °C.

We analyzed chemical composition and electron transport phenomena in surface and sub-surface region of hot-pressed TiN specimens using a combination of X-ray photoelectron spectroscopy (XPS) and elastic-peak electron spectroscopy (EPES) techniques. Both the surface chemical composition and the elements distribution in the bulk of TiN specimens were determined using XPS and XPS depth profiling analysis. In addition to TiN, a mixture of Ti oxynitride (TiOxNy) and TiO2 compounds as well as carbon contaminants have been detected in the surface region of the TiN specimens. The elemental depth-profiles disclosed uniform chemical bulk composition formed mainly by titanium and nitrogen as well as carbon and oxygen contaminants. Surface enrichment of Ti was evidenced as result of Ar ion-induced preferential sputtering of nitrogen. The inelastic mean free path (IMFP) data evaluated from the relative EPES for electron energies 0.5–2 keV were uncorrected for surface excitations and compared with those calculated from the predictive TPP-2M formula for the measured surface composition. Except to the electron energy of 0.5 keV, a good agreement was found between the measured and predicted IMFPs in the TiN specimen. The higher discrepancies in the measured IMFPs at the lowest energy can be explained by the surface excitation effect. The smallest root-mean-square-deviation and the mean percentage deviation of 2.8 A and 14.8%, respectively, were found between EPES IMFP data and those predicted for TiN with respect to the Ni standard.

InGaN layers with multiple quantum wells are widely used as active layers in advanced optoelectronic devices. In the present work, surface properties of some InGaN layers grown on GaN/sapphire substrates by plasma-assisted molecular beam epitaxy were examined. The total indium content incorporated in the crystalline lattice of In0.165Ga0.835N and In0.353Ga0.647N layers grown with a thickness of 70–200 nm was controlled by the growth temperature, and was determined from X-ray diffraction. Auger electron spectroscopy and X-ray photoelectron spectroscopy analysis reveal relatively smaller concentration of In within the surface area than in the bulk of the InGaN layers. The Ar+ XPS depth profile analysis shows the thick InGaN layers to be chemically homogeneous within an analytical area. To determine the electron inelastic mean free path in the layers within the 500–2000 eV range, relative elastic-peak electron spectroscopy measurements with Ni and Au standards were performed. The measured IMFPs were considerably larger than those predicted from the TPP-2M formula. The smallest root-mean-square-deviation and the mean percentage deviation of 9.9 A and 44.5%, respectively, were found between EPES IMFP data and those predicted for the In0.353Ga0.647N layer with respect to the Au standard. This work provided the detailed compositional and chemical changes of InGaN thick layers, and could be useful in solving key issues associated with the growth of high-quality layer with much higher In content.