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It has been studied the morphology of the surface of the semipolar gallium nitride layers synthesized on nano-pattemed Si(100) or Si(113) substrates with a V-shaped or U-shaped surface profile, respectively. The morphology of the surface of the semipolar layers indicates that the different height-to-width ratio of the GaN(11-22) and GaN(10-11) blocks is associated with a higher growth rate of the GAN(11-22) face than GaN(10-11) and with different growth rates of the semipolar and polar crystal faces during the nucleation of the layer on a nano-patterned substrate. [ABSTRACT FROM AUTHOR]

Scanning electron microscopy is used for studies of the initial stages of the formation of semipolar AlN (10 1) and AlN (10 2) layers during metal–organic vapor-phase epitaxy on a Si (100) substrate with a surface, on which a V-shaped nanostructure, whose elements are <100 nm in dimensions, is formed (a NP-Si(100) substrate). It is shown that, in the initial stage of epitaxy on the NP-Si(100) substrate, nuclei of AlN crystals are formed and then, depending on the crystallographic orientation of the V walls, crystals faceted by AlN (10 1) or AlN (10 2) planes are formed, correspondingly, on Si (111) or Si (111) misoriented in the [110] direction by 7°. [ABSTRACT FROM AUTHOR]

Two different approaches to epitaxy of 4-μm-thick layers of polar GaN(0001) and semipolar GaN(10 1) on a V-shaped nanostructured Si(100) substrate with nanometer-thick SiC and AlN buffer layers have been experimentally demonstrated. The GaN(0001) layers were synthesized by hydride vapor-phase epitaxy, and GaN(10 1) layers, by metal-organic vapor-phase epitaxy, with the growth completed by hydride vapor-phase epitaxy. It was shown that layers of the polar GaN(0002) have a longitudinal elastic stress of –0.45 GPa and the minimum full width at half-maximum of the X-ray diffraction rocking curve ωθ ~ 45 arcmin, whereas for the semipolar GaN(10 1), these values are –0.29 GPa and ωθ ~ 22 arcmin, respectively. A conclusion is drawn that the combined technology of semipolar gallium nitride on a silicon (100) substrate is promising. [ABSTRACT FROM AUTHOR]

Epitaxial aluminum nitride (AlN) layers on Si(111) substrates have been grown by sequential application of several techniques including reactive magnetron sputter deposition to a thickness of 20 nm, metalorganic vapor-phase epitaxy (MOVPE) to a total thickness of 450 nm, and hydride vapor-phase epitaxy (HVPE) to a final thickness of 2 μm. Synthesis of AlN layers by this combined method provides a significant decrease in the residual strain and suppresses the formation of cracks in the epilayer. [ABSTRACT FROM AUTHOR]

Abstract: The selective epitaxial growth of GaN by metalorganic vapor-phase epitaxy combined with ion-beam etching is investigated. To this end, partially masked GaN epitaxial layers are fabricated by depositing a thin Si3N4 layer onto the surface in a single technological process with the growth of GaN and the subsequent opening of windows of different shapes in this layer by an ion beam. Selective epitaxial growth regimes are studied. It is shown that, in a situation where the total area of the windows in the mask is small relative to the total area of the sample, the required epitaxy duration should be 5-10 s, which impairs the reproducibility of the parameters of the epitaxial process. It is also shown that the mechanism of the selective growth of submicrometer objects differs significantly from that for planar layers and selectively grown layers with dimensions of ~1 μm or greater. The effect of precursor (trimethylgallium and ammonia) fluxes on the character of selective epitaxy is examined. To investigate the possibilities of varying mask topology for fabricating model objects with regard to photonic crystals, the impact of the shape and orientation of the windows in the Si3N4 mask on the character of selective epitaxy is studied. [ABSTRACT FROM AUTHOR]

Abstract: Our study describes FIB technological aspects of preparing mask for GaN selective area epitaxy on Si3N4/GaN template. [ABSTRACT FROM AUTHOR]

In the Si3N4 layer, coaxial and single submicrometer GaN structures of hexagonal shape with pyramidal facets are formed by selective vapor-phase epitaxy in windows produced with a focused ion beam. It is found that coaxial hexagonal structures are formed during the growth process in ring-shaped mask windows. [ABSTRACT FROM AUTHOR]

Chloride epitaxy of GaN layers in a horizontal reactor is studied numerically. The steady 3D fluxes of the gas mixture in the reactor are simulated with allowance for heterogeneous reactions on the substrate (growth of epitaxial GaN layers) and on the reactor walls (growth of a polycrystalline GaN deposit). Experimental data on the growth rate distribution for polycrystalline and epitaxial GaN layers are explained. It is shown that, if the diameter of the reactor is not large enough, the growth of the deposit on the walls makes the GaN growth rate distribution over the substrate more nonuniform due to the parasitic diffusion of reagents from the gas phase to the reactor walls. [ABSTRACT FROM AUTHOR]

A new approach is described, according to which the use of a thin silicon carbide (SiC) interlayer ensures the suppression of cracking and the simultaneous release of elastic strain in gallium nitride (GaN) epilayers grown by hydride-chloride vapor-phase epitaxy (HVPE) on 1.5-inch Si(111) substrates. Using this method, 20-μm-thick GaN epilayers have been grown by HVPE on Si substrates with AlN (300 nm) and SiC (100 nm) interlayers. A high quality of the obtained GaN epilayers is confirmed by the photoluminescence spectra, where an exciton band with hvmax = 3.45 eV and a half-width (FWHM) of 68 meV is observed at 77 K, as well as by the X-ray rocking curves exhibiting GaN(0002) reflections with a half-width of ωϑ = 600 arc sec. [ABSTRACT FROM AUTHOR]

Mirror-smooth, transparent bulk GaN layers with an area of 2 × 3 cm[SUP2] and a thickness of up to 1 mm were grown by hydrochloride vapor-phase epitaxy. Cracking of the material was eliminated by using a two-stage growth process; separation from a substrate was provided by a low-temperature buffer layer of preset thickness. For the best samples, FWHM of the X-ray rocking curve was ω[SUBθ] = 3.5' and the dislocation density amounted to 10[SUP7]-10[SUP8]cm[SUP-2]. [ABSTRACT FROM AUTHOR]

We have studied epitaxial layers of gallium nitride (GaN) in a template composition grown by surfactant-mediated hydride-chloride vapor phase epitaxy. The surfactant component was provided by 5 mass % additives of antimony and indium to the source of gallium. Comparative analysis of the obtained results shows evidence of the positive influence of surfactants on the morphology of epitaxial GaN layers. [ABSTRACT FROM AUTHOR]

A new method of synthesis of semipolar gallium nitride on a silicon substrate using the technology of solid-phase epitaxy of 3C-SiC nanocrystals has been suggested. It has been demonstrated that application of buffer layers of 3C-SiC and AlN enables one to form epitaxial layers of semipolar gallium nitride with layer deviation from the polar position of the c axis of a wurtzite crystal by an angle of 48°-51° at the minimal half-width of the X-ray diffraction rocking curve (ω) ∼ 24′. The observed bend of a cylindrical character in the structure of GaN/AlN/3C-SiC(001) is explained by the anisotropic deformation of semipolar GaN on silicon. [ABSTRACT FROM AUTHOR]

Gallium nitride (GaN) layers on sapphire substrates have been grown by hydride-chloride vaporphase epitaxy (HVPE) at a Ga-source temperature reduced from 890°C (standard value) to 600°C. All epilayers are transparent and have smooth surfaces. The structural quality of layers was evaluated by measuring the X-ray rocking curve width (FWHM) using a triple-crystal X-ray diffractometer. For the best samples, this quantity amounted to 8 arc min. Analysis of the dependence of the crystal structure quality and photoluminescent properties of GaN layers on the Ga-source temperature showed that a decrease in this parameter to 600°C did not significantly affect the HVPE growth of GaN despite a considerable change in the vapor phase composition (ratio of GaCl and GaCl3 concentrations). [ABSTRACT FROM AUTHOR]

The structure and luminescent properties of gallium nitride (GaN) epilayers grown by hydride-chloride vapor-phase epitaxy (HVPE) in a hydrogen or argon atmosphere on 2-inch Si(111) substrates with AlN buffer layers have been studied. The replacement of hydrogen atmosphere by argon for the HVPE growth of GaN leads to a decrease in the epilayer surface roughness. The ratio of intensities of the donor-acceptor and exciton bands in the luminescence spectrum decreases with decreasing growth temperature. For the best samples of GaN epilayers, the halfwidth (FWHM) of the X-ray rocking curve for the (0002) reflection was 420 sec of arc, and the FWHM of the band of exciton emission at 77 K was 48 meV. [ABSTRACT FROM AUTHOR]