Micropipe healing in SiC wafers by liquid-phase epitaxy in Si-Ge melts

Liquid-phase epitaxy (LPE) of silicon carbide (SiC) was shown to be an effective technique to overgrow micropipe defects (MP) in SiC wafers prepared by the physical vapour transport (PVT) technique. Growth close to thermodynamic equilibrium, e.g. low supersaturation, provides a favourable condition for effective MP healing. Therefore, the aim of this work was to grow epitaxial layers from strongly diluted Si-based solutions. Using the method of horizontal dipping, the dependence of MP elimination efficiency on Si-Ge flux composition and on the crystallographic orientation (on- and off-axis) of the SiC wafer was investigated. High-quality single crystalline SiC layers of a thickness up to 10 put were grown with the growth rate of 0.5 mum/h. On off-oriented wafers, stepped growth morphology was observed independent of the melt composition. Micropipes with the diameter below 5 mum were closed with an efficiency of about 80%. SEM investigations as well as inspection under reflected/transmitted light did not show any specific distortion of the growth morphology at the micropipe healing place. (C) 2004 Elsevier B.V. All rights reserved.