Micropipe density

It is also interesting to note that the technique is shown to reduce micropipes by 80% during each run [35]. The micropipes close at the interface by some type of hollow core-closing effect. Very low micropipe densities have been recorded using this technique, which is clearly much faster in improving material quality than seeded sublimation growth. 

Figure 1.11 Simuiation of the yieid of various sizes of Schottky diodes versus micropipe density for randomiy distributed micropipes. The right-hand figure is a detaii of the ieft-hand figure. Micropipes iocated on the active area or JTE region render a faiied device, however, micropipes iocated in between the devices are considered harmiess.

SiC power devices are expected to be superior to Si devices even at room temperature. However, the practical difficulties are related to a limited yield of large area devices due to the existence of so-called micropipes (or voids) [10]. The density of these micron size defects has steadily decreased over the years reaching approximately 100 to 400 cm 2 in the state-of-the-art 6H-SiC substrates [11]. These defects are formed during the substrate growth. They... 

Recent reviews on the growth of high-purity SiC single crystals and their properties have been given by Muller et al. [195] and Augustine et al. [196]. Today, wafer diameters up to 50 mm are feasible on an industrial scale for the polytypes 4H and 6H the density of micropipe defects can be reduced to less than 100 cm (down to about 1 cm ). 

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