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Saint Petersburg, Russia

Mokhov E.N.,RAS Ioffe Physical - Technical Institute | Wolfson A.A.,RAS Ioffe Physical - Technical Institute | Helava H.,Nitride Crystals Inc. | Makarov Y.,Nitride Crystals Inc. | Makarov Y.,Nitride Crystals Ltd.
Materials Science Forum | Year: 2013

Growth techniques of high quality AlN and GaN bulk crystals on SiC seeds by sublimation sandwich method are presented. GaN crystals were grown in the temperature range of 1100-1250°C and with addition of ammonia (NH3) to prevent GaN decomposition. GaN powder or metallic Ga was used as the source. AlN crystals up to 2 inch diameter have been grown on SiC seeds in the temperature range of 1950-2050°C. Kinetic mechanisms and transport features in the sandwich cell are discussed. The achieved high crystal quality has allowed producing semiconductor devices on their basis, in particular, ultraviolet LEDs. © (2013) Trans Tech Publications, Switzerland.

Evseenkov A.S.,Saint Petersburg Electrotechnical University | Tarasov S.A.,Saint Petersburg Electrotechnical University | Lamkin I.A.,Saint Petersburg Electrotechnical University | Solomonov A.V.,Saint Petersburg Electrotechnical University | Kurin S.Y.,Nitride Crystals Ltd.
Proceedings of the 2015 IEEE North West Russia Section Young Researchers in Electrical and Electronic Engineering Conference, ElConRusNW 2015 | Year: 2015

The UV LED heterostructures have been obtained by HVPE approach and investigated by XRD, AFM and PL methods. The experiment shows that the peak wavelength of UV LEDs is in the range of 360-365 nm with FWHM of 10-13 nm. At operating current of 20 mA the active region temperature Tj is 43 °C, the output optical power and efficiency - 1.14 mW and 1.46 %, respectively. It is presented a model based on corpuscular Monte Carlo method in order to calculate the light extraction index. The simulation results allow us to propose the ways to increase the efficiency of UV LEDs by 3-4 times: surface interfaces texturing, optimization of the design of heterostructures, and the use of lenses. © 2015 IEEE.

Kurin S.,Nitride Crystals Ltd. | Antipov A.,Nitride Crystals Ltd. | Barash I.,Nitride Crystals Ltd. | Roenkov A.,Nitride Crystals Ltd. | And 10 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2014

In this paper, we report on growth of ultraviolet light-emitting diode (UV LED) heterostructures by hydride vapour phase epitaxy (HVPE) on sapphire substrates and results of the heterostructures characterization by X-ray diffractometry, scanning electron microscopy, photo- and electroluminescence, micro-photoluminescence, collected from the cleaved edges and the surface of the heterostructure with lateral resolution of about 1 μm. The heterostructures demonstrate efficient hole injection and low droop of the external quantum efficiency. Packaged 360 nm UV LED chips have wall-plug efficiency of 1-1.5%. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Makarov Y.,Nitride Crystals Inc. | Makarov Y.,Nitride Crystals Ltd. | Litvin D.,Nitride Crystals Ltd. | Vasiliev A.,Nitride Crystals Ltd. | Nagalyuk S.,Nitride Crystals Ltd.
Materials Science Forum | Year: 2016

Recently, the wide bandgap semiconductors, especially silicon carbide (SiC), have become more important due to the unique electrical and thermophysical properties that make them applicable to a variety of electronic devices (Schottky and PiN diodes, JFETs, MOSFETs, etc.). For these applications, the crystals need to be manufactured with highest possible quality, both structural and chemical, at reduced cost. This requirement places rather extreme constraints on the crystal growth as the simultaneous goals of high quality and low cost are generally incompatible. Refractory metal carbide technology, particularly, tantalum carbide (TaC), was originally developed for application in highly corrosive and reactive environments. Yu. Vodakov [1] demonstrated for the first time advantages of use of refractory metal carbides for PVT growth of SiC and later AlN bulk crystals. In the present paper we discuss the effect of refractory metal on PVT growth of large diameter 4H SiC bulk crystals. © 2016 Trans Tech Publications, Switzerland.

Mokhov E.,RAS Ioffe Physical - Technical Institute | Izmaylova I.,RAS Ioffe Physical - Technical Institute | Kazarova O.,RAS Ioffe Physical - Technical Institute | Wolfson A.,RAS Ioffe Physical - Technical Institute | And 6 more authors.
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2013

The features of 2" AlN bulk crystal growth by the sublimation sandwich method (SSM) on SiC seeds in a graphite-heated reactor are investigated. AlN growth conditions and crystal properties are compared with the results of SiC sublimation growth in the same reactor. The specifics of AlN sublimation growth, including insufficient reproducibility of results, are believed to be caused by the low sticking coefficient of molecular nitrogen and the high reactivity of Al vapors. The formation of pores in the AlN crystal is explained by selective sublimation etching of the growing surface. The negative effect of non-optimal growth conditions and impurities on AlN crystal quality is discussed. The analysis of container materials, inert to Al vapors was carried out. Various types of TaC crucibles suitable for growth of bulk AlN crystals on SiC seeds were developed. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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