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The microstructure of gallium nitride epitaxial layers synthesized by hydride vapor phase epitaxy (HVPE) and metalorganic chemical vapour deposition (MOCVD) on nanoprofiled NP‒Si(001) substrates with and without an intermediate 3C‑SiC layer has been investigated by transmission electron microscopy (TEM). It is found that the GaN layer obtained by HVPE on a combined NP–Si(001)/SiC substrate has a relatively smooth surface morphology and satisfies the orientation relationships $${{(\bar {2}\bar {2}0)}_{{Si}}}\,||\,{{(\bar {2}110)}_{{{\text{GaN}}}}}$$ and $${{(2\bar {2}0)}_{{{\text{Si}}}}}\,||\,{{(0\bar {1}10)}_{{{\text{GaN}}}}}$$ with the substrate. At the same time, the GaN layers obtained by MOCVD exhibit a rough surface morphology and a texture with preferred grain orientations $${{[\bar {1}10]}_{{Si}}}\,||\,{{[\bar {2}110]}_{{GaN}}}$$ on the nanoprofiled NP–Si(001) substrate with an angle of ∼4.5° between [111]Si and [0001]GaN and preferred orientations $${{[\bar {1}\bar {1}0]}_{{Si}}}\,||\,{{[\bar {2}110]}_{{GaN}}}$$ and $${{[\bar {1}11]}_{{Si}}}\,||\,{{[0001]}_{{GaN}}}$$ on the combined NP–Si(001)/SiC substrate.

Plastic relaxation of a stressed semipolar AlN( $$10\bar {1}1$$ ) layer synthesized on a nanopatterned Si(100) substrate has been investigated using scanning electron microscopy. It is shown that the application of a nanorelief consisting of triangular nanogrooves with inclined faces close to the Si(111) plane in a semipolar AlN layer can lead to the formation of cracks only in the direction perpendicular to a groove. Model concepts of plastic relaxation of the stressed semipolar layer are based on comparison of the threshold stress, above which cracks appear, with the thermomechanical stresses emerging because of the difference between the thermal expansion coefficients of the AlN/Si structure.

Transmission electron microscopy was used to study the interaction of a + c and a dislocations in a thick (14 μm) semipolar GaN layer grown by hydride vapor phase epitaxy on a 3C-SiC/Si(001) template. It is shown that the propagation of a dislocation half-loop with a Burgers vector b = $$\frac{1}{3}\left\langle {1\bar {2}10} \right\rangle $$ during cooling can be blocked due to its reaction with a threading dislocation with a Burgers vector b = $$\frac{1}{3}\left\langle {\bar {1}2\bar {1}3} \right\rangle $$ with the formation of a dislocation segment with a Burgers vector b = 〈0001〉. The gain in energy of the system as a result of such reaction is theoretically estimated. Within the approximation of dislocation linear tension, this gain is ~7.6 eV/A, which gives ~45.6 keV for new dislocation segment with a length of ~600 nm. The contribution of the energy of the dislocation core is estimated as ~19.1 keV.

Semipolar GaN layers synthesized on a nanostructured Si(100) substrate are studied. It is shown that using a Si(100) nanoprofile combined with SixNy nanostrips on top of nanostructures can yield, via metal-organic chemical-vapor deposition, GaN(10 $$\bar {1}$$ 2) layers. An additional SiC buffer layer makes it possible to obtain GaN(10 $$\bar {1}$$ 1) layers with a full-width at half-maximum of the diffraction-curve of ωθ ≈ 35′ arcmin. It is found that the luminescence properties of the semipolar layers are mostly due to basal plane stacking faults BSFS-I1, in contrast to polar layers in which these properties are mostly due to the recombination of excitons.

Synthesis of AlN and GaN layers on a Si(100) substrate by chloride vapor-phase epitaxy has been considered. The process includes sulfidizing of the silicon surface, nucleation and growth of an AlN layer, and then formation of a GaN/AlN structure. It has been found that in the case of a (100)Si substrate, GaN nucleates on buffer AlN layers that may have two crystallographic orientations in contrast to a Si(111) substrate, on which a buffer layer may have only one orientation. It has been shown that the treatment of the Si(100) substrate in an aqueous solution of (NH4)2S decreases the FWHM of the rocking curve for GaN(0002) by a factor of 1.5.

Initial stages of the semipolar AlN layer formation by chloride-hydride vapor phase epitaxy on a misoriented Si(100) substrate with a thin intermediate nano-SiC layer grown by atomic substitution method are investigated. It is found that once the growth rate of AlN layer on a nano-SiC/Si(100) substrate is about 0.02m/h, the layer is formed in a polar direction. On the other hand, at the growth rate of 1m/h the layer is formed in a semipolar direction. We propose the model of the semipolar AlN layer growth based on the formation of the special structure on the SiC layer synthesized by atomic substitution and on the possibility of the matching of the quasi-lattices of Al(2023) and 3CSiC(100) planes assuming bonding of four atoms from the layer to four atoms of the 3CSiC quasi-lattice consisting of three lattice unit cells in one of the directions. Display Omitted Technology of AlN(2023) synthesis on Si(100) by HVPE is developed.The formation of semipolar or polar AlN depends on the growth rate.The model of the semipolar AlN formation is proposed.

Hydride vapor phase epitaxy (HVPE) growth of semipolar AlN and GaN layers on planar Si(100) substrates with SiC nanolayer is investigated. It is shown experimentally that the solid-phase epitaxial formation of a specially oriented SiC nucleation layer followed by epitaxy of AlN layer by HVPE at low rates enables growth of aluminum and gallium nitrides in the semipolar direction. For the best GaN(20-23) layers obtained, the full width at half maximum (FWHM) value for the x-ray diffraction rocking curve is 24 arcmin. The photoluminescence spectrum of the semipolar GaN measured at 4 K exhibits bands related to basal-plane and prismatic stacking faults (BSF and PSF).

The results of studies of semipolar GaN(10-12) layers synthesized on a nano-patterned Si(100) substrate are presented. It is shown that in the method metalorganic vapor phase epitaxy, the use of a nanorelief consisting of V-shape groove with inclined faces close to the Si(111) plane can lead to the formation of regions of cubic gallium nitride in the nano-groove. Model of the origin of the cubic phase are based on the formation of AlN nuclei in (0001) and (10-10) nano-groove and the conjugation of the AlN(10-10) and c-GaN planes by the “magic mismatch” mechanism.

The synthesis of III-nitride binary compounds on commercial standard (001) silicon wafers by vapour-phase epitaxy is one of the promising directions for III-nitride technology development. However, the difference between crystal symmetry of Si(001) and wurzite (0001) surface structures is challenge that hinders the development. A use of silicon substrates with nano-patterned surface is one of the solutions to the problem. In this paper we present a transmission electron microscopy study of polar and semipolar GaN layers grown by halide vapour-phase epitaxy and metalorganic vapour-phase epitaxy on nano-patterned silicon (001) substrate. Crystallographic orientation relationships between the silicon substrate and GaN layers is identified. For GaN layers grown by metalorganic vapour-phase epitaxy an effect of SiC buffer layer synthesized by original growth method on their microstructure and surface morphology is under consideration.

We present the results of a conventional and high-resolution electron microscopy investigation of thick (up to 15 μm) semipolar GaN layers grown on Si(001) offcut substrates with 3C-SiC and AlN buffer layers. GaN and AlN layers have been grown by chloride vapor phase epitaxy. The silicon carbide buffer layers were produced by a new method of solid-phase synthesis on 4 and 7° offcut Si(001) substrates. It is shown that the use of solid-phase synthesis for the formation of SiC layer allows one to grow a semipolar GaN layer. The asymmetrical defect structure of the semipolar layer is revealed.

Technologies capable of growing semiconducting heterostructures as thin films (∼100A ) are necessary to the development of semiconducting quantum-size electronics. Such structures are presently fabricated mainly by molecular-beam epitaxy and gas-phase epitaxy from organometallic compounds.