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Bulk AlN crystals grown by sublimation on SiC substrates exhibit relatively high dislocation densities. The kind of defect formation at early growth stages influences the structural quality of the grown crystals. In this work, the dislocation distribution near to the interface is understood through investigation of thin (≤1.5 mm) continuous (non-cracked) freestanding crystals obtained in one process with the evaporation of the substrates. The AlN specimens were characterized using synchrotron radiation imaging techniques. We revealed by triple-axis X-ray diffraction study that, near to the former interface, randomly distributed dislocations configured to form boundaries between $$\sim $$ 0.02 $$^{\circ }$$ misoriented sub-grains (from [0001] direction). Threading dislocation structure similar to that in epitaxial GaN films was not detected. To explain these observations, a theoretical model of misfit stress relaxation near the interface is suggested.

The physical vapor transport growth of aluminium nitride (AlN) layers was performed in one process with the evaporation of silicon carbide (SiC) substrates. In this paper, we show that the rate of SiC evaporation is slow in a narrow process window for AlN growth but increases in the presence of AlN vapor. The properties of the substrates influence the evaporation process; therefore an investigation is done to understand this phenomenon. We first describe the evaporation behavior of a SiC substrate depending on its size, thickness, structure and polarity. Then we demonstrate the surface morphology and structural quality of the AlN layers grown on C-polar SiC. In the case of a step-flow growth, our method allows us to obtain thin freestanding layers with moderate dislocation densities and rocking curve widths comparable to those of bulk crystals.

Two sets of undoped GaN films with the thickness of 10–20 μm were prepared by hydride vapor phase epitaxy (HVPE) and characterized by capacitance–voltage ( C – V ) profiling, microcathodoluminescence (MCL) spectra measurements, MCL imaging, electron beam induced current (EBIC) imaging, EBIC dependence on accelerating voltage, deep levels transient spectroscopy, high resolution X-ray diffraction measurements. The difference in growth conditions was mainly related to the lower (850 °C, group 1) or higher (950 °C, group 2) growth temperature. Both groups of samples showed similar crystalline quality with the dislocation density close to 10 8 cm −2 , but very different electrical and optical properties. In group 1 samples the residual donors concentration was ∼10 17 cm −3 or higher, the MCL spectra were dominated by the band-edge luminescence, and the diffusion length of charge carriers was close to 0.1 μm. Group 2 samples had a 2–4.5 μm thick highly resistive layer on top, for which MCL spectra were determined by green, yellow and red defect bands, and the diffusion length was 1.5 times higher than in group 1. We also present brief results of growth at the “standard” HVPE growth temperature of 1050 °C that show the presence of a minimum in the net donor concentration and deep traps density as a function of the growth temperature. Possible reasons for the observed results are discussed in terms of the electrical compensation of residual donors by deep traps.

Results of temperature treatment effect on near surface layer properties of Zn ion implanted Si substrate are presented. Radiation induced point defects and Zn in depth profile was studied by Rutherford back scattering (RBS) method with use of channeling technique. Topology of substrate surface was studied by atomic force microscopy (AFM) and scaning electron microscope (SEM). Phase composition of samples was test by x-ray diffraction in grazing geometry.

The structure and the electrical and magnetic properties of Mn-implanted Si, which exhibits ferromagnetic ordering at room temperature, are studied. Single-crystal n- and p-type Si wafers with high and low electrical resistivities are implanted by manganese ions to a dose of 5 × 1016 cm−2. After implantation and subsequent vacuum annealing at 850°C, the implanted samples are examined by various methods. The Mn impurity that exhibits an electric activity and is incorporated into the Si lattice in interstitial sites is found to account for only a few percent of the total Mn content. The main part of Mn is fixed in Mn15Si26 nanoprecipitates in the Si matrix. The magnetization of implanted Si is found to be independent of the electrical resistivity and the conductivity type of silicon and the type of implanted impurity. The magnetization of implanted Si increases slightly upon short-term postimplantation annealing and disappears completely upon vacuum annealing at 1000°C for 5 h. The Mn impurity in Si is shown to have no significant magnetic moment at room temperature. These results indicate that the room temperature ferromagnetism in Mn-implanted Si is likely to be caused by implantation-induced defects in the silicon lattice rather than by a Mn impurity.

The structure of manganese-implanted (dose 2 × 1016 cm−2) n-type and p-type silicon, ferromagnetic at room temperature, has been studied. During implantation, an amorphized layer is formed in the silicon wafer. Subsequent vacuum annealing improves the structural quality of the implanted material and leads to the formation of a vacancy solid solution of manganese in silicon. A difference in the degree of structural quality of silicon implanted by different impurities has been experimentally established.

Microdefects in undoped and zinc-doped GaP single crystals grown by the liquid-encapsulation Czochralski method have been studied by X-ray diffuse scattering. In undoped GaP single crystals, deviation from stoichiometry increases from the beginning to the end of an ingot. The ingot end is characterized by enhanced precipitation of excess gallium with formation of platelike microdefects. With an increase in their size, stress relaxation around microdefects begins to manifest itself. Doping with zinc leads to a significant change in the microdefect formation pattern.

A high resolution X-ray diffraction method has been effectively used for the structural characterization of InP porous layers. It was revealed that strong diffuse scattering from pores around reciprocal lattice points does depend on the azimuth positions of samples. To extract structural information about porous layers fabricated under different conditions theoretical analysis of the measured reciprocal space maps (RSM) was performed. The statistical dynamical X-ray diffraction theory was used to describe coherent and diffuse scattering from a layer with cylindrical pores. A numerical analysis of the RSMs for two azimuth positions φ (φ = 0 and φ = 90°) and detailed sections of RSMs (linescans) allowed determination of the radius, the length of the pores and tilting angle with respect to the surface normal.

The effect of in situ photoexcitation on the generation of structure defects in Si crystals implanted by Ar+ and Ne+ ions was studied using high-resolution x-ray diffraction. Photoexcitation was found to decrease the residual concentration of radiation-induced point defects in the case of low radiation damage (low doses, high energies) leading to annihilation of Frenkel pairs. For heavy damage (high doses, low implantation temperatures, low energies), photoexcitation contributes to amorphization of the damaged layer, which manifests itself as the formation and growth of clusters of radiation-induced point defects. Thus, in situ photoexcitation speeds up secondary processes, and the predominance of one or other process is stipulated by the degree of supersaturation of the solid solution of radiation-induced point defects.

Diffuse x-ray scattering (DXS) is used to study the formation of microdefects (MDs) in heat-treated dislocation-free large-diameter silicon wafers with vacancies. The DXS method is shown to be efficient for investigating MDs in silicon single crystals. Specific defects, such as impurity clouds, are found to form in the silicon wafers during low-temperature annealing at 450°C. These defects are oxygen-rich regions in the solid solution with diffuse coherent interfaces. In the following stages of decomposition of the supersaturated solid solution, oxide precipitates form inside these regions and the impurity clouds disappear. As a result of the decomposition of the supersaturated solid solution of oxygen, interstitial MDs form in the silicon wafers during multistep heat treatment. These MDs lie in the {110} planes and have nonspherical displacement fields. The volume density and size of MDs forming in the silicon wafers at various stages of the decomposition are determined.

A complex investigation into the structural perfection of the Si/SiGe superlattices grown by molecular-beam epitaxy at different temperatures of the Si substrate has been carried out by high-resolution X-ray diffraction analysis, secondary ion mass spectrometry (SIMS), and transmission electron microscopy (TEM). It is demonstrated that the combination of these methods makes it possible to describe in sufficient detail the distributions of the strains and Ge concentrations in the elastically strained superlattices and also to evaluate the sharpness of the layer interfaces. It is shown that the densitometry of electron microscope images of the superlattice cross-sections permits characterization of the relative sharpness of the layer interfaces and a qualitative representation of the Ge distribution throughout the thickness of the SiGe layers.

The state of manganese impurity in implanted silicon at implantation doses of up to 5 × 1016 cm−2 has been investigated by X-ray diffraction and transmission electron microscopy. It is established that, after short-term vacuum annealing at 850°C, most of the implanted manganese impurities are in microinclusions up to 20 nm in size formed by a tetragonal silicide phase of the Mn15Si26 type.