Facets in GaSb crystals pulled under concave interface conditions

Abstract

Central and peripheral facets are occasionally found in the end part of Te-doped GaSb crystals pulled under non-steady state growth conditions when the growth interfaces are concave toward the melt. The central faceted region is continuously grown and is a helical shape owing to the temperature fluctuation caused by crystal rotation. The microscopic growth rate in this facet changes periodically. The central facet is essentially different from that on the convex growth interfaces, and does not result from the shift of the location of a faceted region which originated on the concave interfaces at the crystal edge. The coexistence of both central and peripheral faceted regions is not recognized on the same concave curved planes. The growth mechanism of the central facet on the concave interfaces is not understood at present.