Engel’-Yurt, Russia
Engel’-Yurt, Russia

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Makarov Yu.N.,Nitride Crystals Group Ltd. | Litvin D.P.,Nitride Crystals Group Ltd. | Vasiliev A.V.,Nitride Crystals Group Ltd. | Segal A.S.,Soft Impact | And 4 more authors.
Materials Science Forum | Year: 2010

In this paper, we report on the current status of our technology for the commercial production of 3″ 6H-SiC substrates, including PVT growth [1] of more than 3″ diameter and up to 20 mm long 6H-SiC boules, post-growth processing of the boules, and characterization of the produced wafers. We discuss the preparation of SiC sources and seeds, the initial transient stage of the growth, the distribution of temperature in the growth crucible, and the Si/C ratio in the vapor. Special attention is given to the rise of the process stability and the reduction of crystallographic defects, including micropipes (open core screw dislocations), low-angle grain boundaries, foreign polytype inclusions, and graphite inclusions [2,3]. © (2010) Trans Tech Publications.

Usikov A.,Nitride Crystals Inc. | Usikov A.,Saint Petersburg State University of Information Technologies, Mechanics and Optics | Kurin S.,Nitride Crystals Group Ltd. | Barash I.,Nitride Crystals Group Ltd. | And 7 more authors.
Materials Science Forum | Year: 2016

Hydride Vapor Phase Epitaxy (HVPE) was used to grow 1-4 μm thick undoped GaN layers on 4H-SiC and sapphire substrates. To adjust mechanical strain and crack formation in the GaN/SiC samples, the AlGaN-based buffer layer was grown at low temperature (920-980ºC) and the GaN layer was grown at a higher temperature (1000-1040ºC). Laser scribing through the GaN layer or the SiC substrate was applied to fabricate dies from the GaN/SiC and GaN/sapphire samples. The laser irradiation passing through the GaN layer to the sapphire substrate or through the SiC substrate to the GaN layer, along two orthogonal directions created a net of micro-cavities in sapphire and melted grooves in SiC that promote easy breakage of the sample into rectangular dies. © 2016 Trans Tech Publications, Switzerland.

Medvedev O.S.,Saint Petersburg State University | Khait O.,Multitech Ltd. | Kurin S.Yu.,Nitride Crystals Group Ltd. | Usikov A.S.,Nitride Crystals Inc. | And 3 more authors.
Journal of Physics: Conference Series | Year: 2015

We report on intra-volume laser scribing process developed for GaN layers grown on single-side and double-side c-plane sapphire structures by hydride vapor phase epitaxy. Dies of 10 mm × 10 mm and 15 mm × 15 mm were cut from 2-inch wafers using a 1.064-μm Nd:YAG pulsed laser. The impact of laser cutting on the mechanical properties of GaN/Al2O3 structures is discussed.

Evseenkov A.S.,Saint Petersburg Electrotechnical University | Tarasov S.A.,Saint Petersburg Electrotechnical University | Kurin S.Yu.,Nitride Crystals Group Ltd. | Usikov A.S.,Nitride Crystals Inc. | And 4 more authors.
Journal of Physics: Conference Series | Year: 2015

The UV LED GaN/AlGaN heterostructures obtained by HVPE approach were investigated. It was shown that the peak wavelength of UV LEDs was in the range of 360-380 nm with FWHM of 10-13 nm. At operating current of 20 mA, the active region temperature Tj was 43°C, the output optical power and efficiency - 1.14 mW and 1.46%, respectively. It was shown that the use of HVPE method allowed to achieve a high degree of structural perfection of epitaxial structures. © Published under licence by IOP Publishing Ltd.

Shabunina E.I.,RAS Ioffe Physical - Technical Institute | Levinshtein M.E.,RAS Ioffe Physical - Technical Institute | Kulagina M.M.,RAS Ioffe Physical - Technical Institute | Kurin S.Yu.,Nitride Crystals Group Ltd. | And 9 more authors.
Journal of Physics: Conference Series | Year: 2015

Multifractal analysis was applied to characterize quantitatively nanostructural disordering in HVPE-grown AlGaN/GaN UV LED structures. A higher level of leakage currents shunting the active region of LEDs by an extended defect system is correlated with higher values of multifractal parameters (MFs). As a result, the concentration of injected carriers participating in radiative recombination in the active region is reduced. MFs and the conductivity of quasi-ohmic shunts localized in an extended defect system are higher in AlGaN/GaN structures than in InGaN/GaN structures. It is one of the reasons behind the low external quantum efficiency of AlGaN/GaN UV LEDs.

Puzyk M.V.,Herzen University | Usikov A.S.,Nitride Crystals Inc. | Kurin S.Yu.,Nitride Crystals Group Ltd. | Puzyk A.M.,Herzen University | And 7 more authors.
Journal of Physics: Conference Series | Year: 2015

GaN layers of n-type and p-type conductivity grown by HVPE on sapphire substrates were used as working electrodes for water electrolysis, photoelectrolysis and hydrogen gas generation. Specifically the water splitting process is discussed. Corrosion of the GaN materials is also considered. The hydrogen production rate under 365-nm UV LED irradiation of the GaN and external bias was 0.3 ml/(cm2∗h) for an n-GaN photoanode (n∼8×1016 cm-3) in 1M Na2SO4 electrolyte and 1.2 ml/(cm2∗h) for an n-GaN photoanode (n∼1×1017 cm-3) in 1M KOH electrolyte.

Reshchikov M.A.,Virginia Commonwealth University | Usikov A.,Nitride Crystals Inc. | Helava H.,Nitride Crystals Inc. | Makarov Y.,Nitride Crystals Inc. | And 3 more authors.
Journal of Electronic Materials | Year: 2016

Gallium nitride, grown by hydride vapor phase epitaxy and capped with a thin AlGaN layer, was studied by photoluminescence (PL) methods. The concentration of free electrons in GaN was found from the time-resolved PL data, and the concentrations of point defects were estimated from the steady-state PL measurements. The intensity of PL from GaN decreases moderately after capping it with Si-doped AlGaN, and it decreases dramatically after capping with Mg-doped AlGaN. At the same time, the concentration of free electrons and the concentrations of main radiative defects in GaN are not affected by the AlGaN capping. We demonstrate that PL is a powerful tool for nondestructive characterization of semiconductor layers buried under overlying device structures. © 2015, The Minerals, Metals & Materials Society.

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