Elastic Interaction of Micropipes in Crystals

Abstract

The stress field, strain energy and interaction force are calculated for an isolated pair of straight parallel screw dislocations, one or both of which is (are) associated with (a) micropipe(s). The effect of the attraction of two dislocated micropipes (or a dislocated micropipe and a full-core screw dislocation) with Burgers vectors of the same sign is examined in detail. An analytical expression for the critical distance below which a dislocated micropipe attracts a fullcore screw dislocation is found. It is shown that two parallel dislocated micropipes with the same signs of the Burgers vectors may attract each other if the distance between the micropipes is small enough and the ratios of the micropipe radii and the Burgers vector magnitudes are sufficiently different. The stress field and strain energy of a dislocated micropipe near a planar free surface and the force of the interaction between the micropipe and the free surface are also found.

Influence of the growth interface shape on the defect characteristics in the facet region of 4H-SiC single crystals

“…More conceivable is an interaction of the MPs leading to an increased distance between them during the growth. As MPs with a burgers vector of equal sign repel each other [16] one of the MPs is bent away from the other in the {11 � 00} plane.…”

Structural transformation of lattice defects in free-spreading growth of bulk SiC crystals

“…Similar models of micropipes attraction to and agglomeration at the boundaries of foreign SiC polytypes were considered in ref. 18 and 31. Third, the planar defects can just be obstacles on the way of micropipes elastically interacting 32,33 with each other, as sketched in Fig. 9.…”

Contact‐free reactions between micropipes in bulk SiC growth

“…The first term in (2) denotes the force exerted by the external stress τ yz given by (1). In brackets of formula (2), the first and second terms correspond to the interactions of the emitted dislocation with dislocations within micropipes MP1 and MP2, respectively; the third–fourth and fifth–sixth terms correspond to the image force 27, 28 exerted by the surface of MP1 and MP2, respectively.…”

“…It is worth noting that formula (3) is valid in the limit of $d\gg r_{1} ,r_{2} $ only (which is the case of the present work). When MPs are close enough (say, $d\leq r_{1} ,r_{2} $ ), one should use a much more complicated expression for Δ W based on the strict solutions of boundary‐value problems for screw dislocations inside two closely spaced micropipes 28 and in between of them 30. It is rather cumbersome, so we do not show it here.…”