Experimental studies on aluminum (Al) and boron (B) implantation in 4H/6H SiC are reported; the implantation is conducted at room temperature or elevated temperatures (500 to 700 °C). Both Al and B act as “shallow” acceptors in SiC. The ionization energy of these acceptors, the hole mobility and the compensation in the implanted layers are obtained from Hall effect investigations. The degree of electrical activity of implanted Al/B atoms is determined as a function of the annealing temperature. Energetically deep centers introduced by the Al+/B+ implantation are investigated. The redistribution of implanted Al/B atoms subsequent to anneals and extended lattice defects are monitored. The generation of the B‐related D‐center is studied by coimplantation of Si/B and C/B, respectively.

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Silicon carbide, a potentially powerful device material, suffers from microscopic hollow defects called micropipes. Their nature is not satisfactorily clarified yet. Our analysis shows that they are hollow core dislocations according to Frank's model, but contain dislocations of mixed type.[S0031-9007 (97)05011-4] PACS numbers: 61.72.Bb, 61.16.Ch, 61.72.Ff, 61.72.LkMicropipes are hollow tubes penetrating SiC single crystals along their growth direction ([1], for review see, e.g., [2]) and occur very frequently in SiC. They can be interpreted in the framework of Frank's model of a hollow core dislocation [3,4]: When the magnitude of the Burgers vector of a dislocation exceeds a critical value (approximately 1 nm) it is energetically more favorable to remove the highly strained material around the dislocation line and to create an additional free surface in the shape of a tube. The relation between the equilibrium radius r 0 and the length of the Burgers vector B in the micropipe is given by Frank's formula,(1) m: shear modulus (for SiC: m 1.9 3 10 11 J͞m 3 ); g: surface energy of the inner surface of the micropipe. We will use this surface energy as a fit parameter in the following discussion. We have to note here that Frank's model is applicable to any type of dislocation. However, in the past, because of the easy accessibility, only screw components were considered [4-6] and the obtained results were consequently discussed in terms of "screw dislocations." In the following discussion we will first adopt this notion and present our results in this familiar picture, but later we must modify it by considering an additional edge component of the Burgers vector. In this case, the shear modulus m in Eq. (1) has to be replaced by the appropriate energy factor K we take for Poisson's ratio y 0.16 [7].In former papers [4,5] we investigated by atomic force microscopy (AFM) growth spirals with micropipes in

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