GROWTH DEFECTS AND LATTICE STRAINS IN LEC-GROWN SINGLE CRYSTALS OF InAsP.

Defect structures and lattice strains in LEC-grown bulk single crystals of InAs//xP//1// minus //x (x equals 0. 1 approximately 0. 3) have been characterized by X-ray diffraction topography using synchrotron and classical sources. A crystal ingot with a left bracket 1 OVER BAR 1 OVER BAR 1 OVER BAR right bracket growth axis consists of a relatively perfect center core surrounded by a less perfect outer region. While the core involves striations and dislocations at all growth levels, the outer region undergoes extended slips in the bottom half of the ingot. The lattice parameter increases at a nearly constant rate toward the ingot tail, with a characteristic expansion at the core center, both being ascribable to a non-uniform arsenic distribution. The observed lattice bending in the core part demonstrates the considerable internal stress present in the crystal.