Process Induced Extended Defects in SiC Grown via Sublimation
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Process Induced Extended Defects in SiC Grown via Sublimation R. Yakimova1, M. Syväjärvi1, H. Jacobson1, R.R. Ciechonski1, N. Vouroutzis and J. Stoemenos 1 Department of Physics and Measurement Technology, Linköping University, SE-58183 Linköping, Sweden Physics Department, Aristotele University of Thessaloniki, 54124 Thessaloniki, Greece ABSTRACT Three possible situations of extended defect formation during sublimation growth of SiC have been investigated: a-plane growth, occurrence and effect of irregular growth interfaces, and development of elongated open volume morphological defects. While in the first case the most preferred defects are basal plane stacking faults (SFs), in other studied samples threading dislocations and high energy SFs have been revealed, these suggesting stress accumulated in the course of the growth process. Formation of morphological defects of the above character has been observed in the presence of micropipes and step flow growth mode on vicinal surfaces. Growth on atomically flat surfaces can eliminate this type of defects but the polytype uniformity is more difficult to maintain. INTRODUCTION Wide band gap (WBG) semiconductors are the materials of future electronics. During the last decade a great deal of effort has been devoted to the development of material and device technologies of silicon carbide (SiC) and III-nitrides. To date SiC is the most advanced candidate to replace conventional semiconductors in high power electronics technology, e.g. motor controllers and power distribution in electric vehicles, as well as in high frequency power controllers and converters [1]. The physical and chemical properties of silicon carbide are excellent for high temperature, power control and high-speed communication devices. It is expected that GaN-based devices grown on SiC substrates will meet the demand of satellite communications for small size devices operating at higher powers than current Si or GaAs based devices. Besides the wide band gap (~3 ev) leading to low intrinsic carriers at elevated temperatures (500oC), SiC has excellent thermal conductivity (~2.5 times that of Si), high breakdown field strength (10 times that of Si) and high saturated electron drift velocity (~2 time that of Si). Silicon carbide is chemically stable (no acid can attack it), radiation hard and thus it is promising for applications in robust conditions. It is also worth noting that SiC is the only WBG semiconductor that has a native oxide. The main advantage of SiC compared to GaN, however, is the availability of substrates allowing homoepitaxial growth of layers and structures needed for fabrication of different devices. Presently, 4H-SiC and 6H-SiC wafers are available up to 3-inch diameter on the market, in both low resistivity and semi-insulating forms [2]. Wafers with 100mm in diameter have been demonstrated [3]. Epitaxial layers can be grown with high growth rate to a thickness of over 100 µm [4,5]. The high power electronics technology will aim at megawatt power levels. This implies blocking vol
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