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Nanoscale-thick films, including high-k dielectrics, are an essential element of modern electronic devices (e.g., transistors based on III–V semiconductors). In this regard, the development of techniques for studying the electronic properties of such nano-objects is an important task. In this work, we propose a technique that makes it possible to determine the presence of trap levels, their concentration, and the activation energy for films up to 40 nm thick. The mechanism of charge transport in high-k dielectrics, such as HfO2, is the subject of active study. We investigated thin hafnia films grown on the Si surface with TEMAH-H2O or Hf-(thd)4-O2 precursor systems. It was shown by X-ray photoemission spectroscopy that the TEMAH-H2O sample was grown with oxygen deficiency. On the Hf-(thd)4-O2 sample, the SiO2 sublayer between hafnia and substrate was formed, which was confirmed by Kelvin probe microscopy and X-ray reflectivity studies. This SiO2 sublayer significantly affects the charge dissipation. Diffusion in the lateral direction along the SiO2 sublayer has a higher diffusion coefficient than in the HfO2 layer, but the presence of the SiO2 sublayer reduces the level of charge leakage to the substrate. The activation energies for hole traps and electron traps were found to be Ea ≈ 0.46 ± 0.03 and 0.37 ± 0.03 eV for the TEMAH-H2O sample and Ea ≈ 0.22 ± 0.05 and 0.16 ± 0.04 eV for the Hf-(thd)4-O2 sample, respectively. It was also shown that the process of positive charge localization occurs faster than negative charge localization. Electron localization leads to a decrease of the intensity of the 2.65 eV CL band, associated with oxygen vacancies. [ABSTRACT FROM AUTHOR]

We have elucidated the microstructure of Al0.28Ga0.72As0.972Sb0.028 metamaterial containing a developed array of AsSb nanoinclusions. The AlGaAsSb films were grown by low-temperature molecular-beam epitaxy followed by high-temperature postgrowth thermal treatment. The process resulted in an array of self-organized AsSb nanoinclusions with an average diameter of 15 nm (after annealing at 750 °C), which occupied about 0.003 of the volume of the crystalline AlGaAsSb matrix. The nanoinclusions were found to have an A7-type rhombohedral microstructure and contained a very high concentration of antimony that exceeded 90%, whereas the Sb content in the AlGaAsSb matrix was 2.8 at. %. The strong enrichment of the inclusion with Sb resulted from the local thermodynamic equilibrium between the solid AlGaAsSb matrix and the As0.1Sb0.9 inclusions that became liquid at an annealing temperature of 750 °C. The inclusion-matrix orientation relationship was established to be (003)p || {111}m and [ 2 ¯ 110 ] p || 〈220〉m, similar to that for pure As precipitates in low-temperature grown GaAs despite a rather large difference in particle lattice constants and the c/a ratio. The increased inclusion-matrix lattice mismatch resulted in the generation of (001) prismatic dislocation loops associated with the inclusions bigger than 8.5 nm in diameter. The Burgers vector of the dislocation was determined as b = amatrix[001]. The established microstructural and compositional features create an opportunity to specify plasmonic resonance conditions in the low-temperature grown AlGaAsSb metamaterial. [ABSTRACT FROM AUTHOR]

AlGaAsSb and AlGaAs films as thick as 1 μm with Al content as high as 60% were successfully grown by low-temperature (200 °C) MBE. To overcome the well-known problem of growth disruption due to a high aluminum content and a low growth temperature, we applied intermittent growth with the temperature elevation to smooth out the emerging roughness of the growth front. Post-growth annealing of the obtained material allowed us to form a developed system of As or AsSb nanoinclusions, which occupy 0.3–0.6% of the material volume. While the As nanoinclusions are optically inactive, the AsSb nanoinclusions provide a strong optical absorption near the band edge of the semiconductor matrix due to the Fröhlich plasmon resonance. Owing to the wider bandgap of the grown Al0.6Ga0.4As0.97Sb0.03 compound, we have expanded the spectral range available for studying the Fröhlich plasmon resonance. The grown metamaterial represents an optically active medium of which the formation process is completely compatible with the epitaxial growth technology of semiconductors. [ABSTRACT FROM AUTHOR]

AlxGa1−xN layers (x = 0.6−0.75) grown using plasma‐assisted molecular beam epitaxy with alternating metal‐enriched stoichiometric conditions using an off‐centered nitrogen flux demonstrate sharp compositional modulation with the formation of monolayer (ML)‐thick Ga‐enriched quantum disks embedded in a Ga‐depleted AlGaN matrix. These structures have a constant modulation period of ≈3 ML over the entire surface of a 2‐inch substrate, and the modulation amplitude increases from zero to maximum with distance from the center of the substrate. This is confirmed experimentally by conventional and scanning transmission electron microscopes, as well as studies of optical absorption and photoluminescence (PL) mappings. The PL measurements also show a high efficiency of ultraviolet‐C (UVC) radiative recombination at room temperature in these layers with an atomically smooth surface topology, emitting in the spectral range 250–290 nm with the maximum ratio of PL intensities measured at high (310 K) and low(10 K) temperatures up to 58%. Moreover, these layers demonstrate stimulated emission with the lowest threshold optical power density of 240 kW·cm−2 (at 287 nm) for the Al0.6Ga0.4N layer with the highest degree of compositional modulation. The results obtained can be used to develop technologies for growing ML‐scale heterostructures in (Al,Ga)N material system. [ABSTRACT FROM AUTHOR]

Densities of a- and a+c-type threading dislocations for a series of GaN films grown in different modes by metalorganic vapor phase epitaxy are determined from the x-ray diffraction profiles in skew geometry. The reciprocal space maps are also studied. Theory of x-ray scattering from crystals with dislocations is extended in order to take into account contribution from both threading and misfit dislocations. The broadening of the reciprocal space maps along the surface normal and the rotation of the intensity distribution ellipse is attributed to misfit dislocations at the interface. We find that the presence of a sharp AlN/GaN interface leads to an ordering of misfit dislocations and reduces strain inhomogeneity in GaN films. [ABSTRACT FROM AUTHOR]