Sumathi, R. Radhakrishnan; Gille, Peter
Development and Progress in Bulk c-Plane AlN Single-Crystalline Template Growth for Large-Area Native Seeds.
In: Japanese Journal of Applied Physics, Vol. 52, No. 8, 2, SI
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28-mm diameter free-standing AlN substrates were obtained from singlecrystalline templates grown hetero-epitaxially on (0001) SiC substratesby the sublimation method. The grown template crystals have fairly highstructural quality with X-ray rocking curve FWHM values of 120 and 200arcsec for symmetric and asymmetric reflections, respectively and anaverage etch pit density of about 5 x 10(5) cm(-2). In Ramanspectroscopy, the E-2(high) phonon mode peak FWHM is 18 cm(-1) and itsposition shift shows a very low tensile strain of similar to 1.5 x10(-4) in the crystals. The presence of Si and C impurity-related localvibrational modes is observed. These impurities might be responsible for lowering the optical absorption band edge to 4.3 eV. Homo-epitaxialgrowth of 5-mm-thick bulk crystals, using 10 mm diameter seeds preparedfrom these templates demonstrates their suitability as native seeds for further growth. (C) 2013 The Japan Society of Applied Physics