The generation of crystal defects in Ge-on-insulator (GOI) layers in the Ge-condensation process

Abstract

The formation process of crystal defects in a Ge-on-insulator (GOI) layer fabricated by oxidizing a SiGe-on-insulator (SGOI) layer, known as the Ge-condensation technique, is studied systematically. It is found that the crystal defects in the GOI layer are threading dislocations and microtwins that are formed mainly in the Ge fraction range larger than ∼0.5. Also, when the Ge fraction reaches ∼1 and the GOI layer is formed, the density of microtwins significantly decreases and their width considerably increases. The relaxation of compressive strain, observed in SGOI and GOI layers, is not attributable to the formation of the microtwins, but to the perfect dislocations that cannot be detected as defects in the lattice image.