We calculate the critical thickness for misfit dislocation (MD) formation in lattice mismatched semipolar and nonpolar III-nitride wurtzite semiconductor layers for the case of MDs originated from prismatic slip (PSMDs). It has been shown that there is a switch of stress relaxation modes from generation of basal slip originated MDs to PSMDs after the angle between c-axis in wurtzite crystal structure and the direction of semipolar growth reaches a particular value, e.g., ∼70° for Al0.13Ga0.87N/GaN (h0h̄1) semipolar heterostructures. This means that for some semipolar growth orientations of III-nitride heterostructures biaxial relaxation of misfit stress can be realized. The results of modeling are compared to experimental data on the onset of plastic relaxation in AlxGa1−xN/GaN heterostructures.

We consider the stress–strain state in α-Ga2O3/α-Al2O3 heterostructures, in which both constituting phases belong to trigonal crystal system. We utilize the hexagonal geometry (hexagonal cell) to account for structural features of the materials and include in the analysis the complete set of six elastic constants Cij being typical for materials with rhombohedral crystal structure that differs from materials with hexagonal one by the presence of an additional constant C14. This allows us to derive analytical formulas for elastic strains and mechanical stresses in pseudomorphic α-Ga2O3 films on α-Al2O3 substrates with various growth orientations assuming nonzero constant C14.

Cohorts of amyotrophic lateral sclerosis (ALS) patients and control individuals of Caucasian origin from the Central European Russia (Moscow city and region) were analyzed for the presence of hexanucleotide repeat GGGGCC expansion within the first intron of the C9ORF72 gene. The presence of a large (>40) repeat expansion was found in 15% of familial ALS cases (3 of 20 unrelated familial cases) and 2.5% of sporadic ALS cases (6 of 238) but in none of control cases. These results suggest that the frequency of C9ORF72 hexanucleotide repeats expansions in the Central European Russian ALS patients is significantly lower than in Western European or Northern American ALS patients of Caucasian origin but higher than in Asian ALS patients.

A method for the growth of high‐quality gallium oxide (β‐Ga2O3) bulk crystals from the melt is developed. The influence of the atmosphere in the process zone on the stability of growth and the quality of Czochralski grown crystals is studied. The structural properties of the crystals obtained are investigated. Samples of gallium oxide substrates are demonstrated. The possibility of growing bulk crystals of solid‐solution oxides (AlxGa1–x)2O3 is tested.

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We present an analytical model describing misfit stresses relaxation in semipolar III-nitride heterostructures caused by misfit dislocations (MDs) originating from basal or prismatic slip and by sessile MDs. We analyze the critical thickness hc for the formation of MDs depending on crystal lattice mismatch and orientation of the semipolar growth plane. We explore transversely isotropic elasticity solutions to describe the relaxation processes in III-nitride semipolar heterostructures and compare the results for hc with those calculated within the isotropic elasticity approach. We find that the value of angle ϑ between the polar с-axis, and the direction of heterostructure growth has an impact on the realization of the stress relaxation mechanism by the generation of MDs originating either from basal or prismatic slip. A comparison of theoretical calculations with experimental data on the observation of MDs in the III-nitride heterostructures is provided.