Cryst. Res. Technol. 42, No. 12, 1232 – 1236 (2007) / DOI 10.1002/crat.200711011 © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Initial stages of SiC crystal growth by PVT method E. Tymicki* 1 , K. Grasza 1,2 , R. Diduszko 1 , R. Bożek 3 , and M. Gała 1 1 Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-991 Warsaw, Poland 2 Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland 3 Institute of Experimental Physics, Faculty of Physics, Warsaw University, ul. Hoża 69, 00-681 Warsaw, Poland Received 21 May 2007, accepted 7 August 2007 Published online 10 November 2007 Key words silicon carbide, physical vapor transport, initial stage of crystal growth, crystallization centres. PACS 81.10.Bk, 81.10.-h Initial stages of SiC crystal growth by Physical Vapor Transport method were investigated. The following features were observed: (a) many nucleation crystallization centres appeared on the seed surface during the initial stage of the growth, (b) at the same places many separate flat faces generated on the crystallization front, (c) the number of facets was dependent on the shape of the crystallization front and decreased during growth, (d) appearance of many facets lead to decrease of structural quality of crystals due to degradation of regions where crystallization steps from independent centres met. The results revealed that the optimal crystallization front should be slightly convex, which permits the growth of crystals with single nucleation centre and evolution of single facet on the crystallization front. The subjects of study were the shape and the morphology of growth interface. Defects in the crystallization fronts and wafers cut from the crystals were studied by optical microscopy, atomic force microscopy (AFM) combined with KOH etching and X-ray diffraction. © 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1 Introduction Silicon carbide is a promising material for high power devices application due to its wide band gap, high thermal conductivity and high breakdown field [1]. The reduction of structural defects, such as micropipes, dislocations and mosaic structure is the main challenge during the growth of SiC crystals. Growth of SiC crystals by Physical Vapor Transport (PVT) method demands best quality seeds. The wafers used as a seeds are obtained from the best parts of the commercially grown crystals or in special growth runs, which are focused on improvement of the structural properties of the crystals. The growth conditions reducing the growth-induced defects are close to equilibrium [2,3] with slow growth rate and carefully prepared source material [4]. The controlling of nucleation and propagation of defects is effective if special attention is paid to parasitic polytype nucleation at the initial stages of growth and during subsequent growth in the presence of facets [5,6]. The highly effective polytype control was used by leading manufacturers to successful elimination of micropipes induced by seed material and formed during growth [6]. However, there is lack of analysis of the evolution of crystallization front morphology in the initial stage of the growth. The transition between flat (polished surface of the seed) and convex (equilibrium shape of the growing crystal) shape of the crystallization front is not fully understood part of the crystal growth run. Defects formed on the beginning of crystal growth would be inherited in the course of further crystallization, forming a great number of crystallization centres, which can contribute to the formation of grain boundaries. Therefore, investigation of the initial stage of crystal growth is necessary for optimization of the growth method. ____________________ * Corresponding author: e-mail: Emil.Tymicki@itme.edu.pl