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The technology of sublimation growth of 15 mm diameter bulk single AlN crystals is scaled to grow similar 2‐inch diameter crystals. The best results are currently achieved with the two‐stage technique including 1) seeding and initial growth of 2‐3 mm thick single‐crystal AlN layers on 2‐inch diameter 6H‐SiC wafers in pre‐carbonized Ta crucibles in graphite equipment and 2) growth of bulk AlN crystals on the above AlN layers in tungsten crucibles and equipment. The initial AlN layers prove of good crystallographic quality but may contain up to 6 at.% of Si impurities. The eventual bulk AlN crystals consist of about 40 mm diameter round single‐crystal core and polycrystalline rim. No impurities in concentration higher than 0.01 at.% are found in the bulk crystals. The bulk AlN crystal may be separated from the initial AlN layer to use the latter repeatedly for growth of a new crystal. Such “secondary” crystals were found to be semi‐insulating. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Aluminum nitride (AlN) is a true bulk‐grown native substrate for III‐nitrides. The crystals are grown by seeded physical vapor transport (PVT) using AlN seeds. AlN has high thermal conductivity (comparable to, and perhaps higher than SiC), high bulk resistivity (>1x1011 Ohm cm), high bulk‐breakdown field (7‐8 MV/cm), the highest surface acoustic wave (SAW) velocity and since it has the smallest lattice constant of the III‐nitrides all AlInGaN compositions grown on AlN are in compression, thus making it easier to grow crack‐free epitaxy. Additionally, AlN is transparent down to nearly 200 nm, making it attractive for deep UV LED structures. AlN has excellent cleavage planes making it suitable for edge‐emitting lasers and low cost manufacturing. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Silicon carbide (SiC) hosts many interesting defects that can potentially serve as qubits for a range of advanced quantum technologies. Some of them have very interesting properties, making them potentially useful, e.g. as interfaces between stationary and flying qubits. Here we present a detailed overview of the relevant properties of the spins in silicon vacancies of the 6H-SiC polytype. This includes the temperature-dependent photoluminescence, optically detected magnetic resonance (ODMR) and the relaxation times of the longitudinal and transverse components of the spins, during free precession as well as under the influence of different refocusing schemes.

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)