New Relaxation Mechanism Enabling High-Quality, Laterally Grown Ge on Si

Abstract

We demonstrate a novel growth technique, metal-catalyzed, lateral epitaxial growth, to grow Ge films laterally on Si with reduced threading dislocation densities (TDD). In contrast to traditional planar film growth on Si, this technique starts with a small crystal nucleation at a specific position on Si followed by Ge lateral film growth. In plan-view and cross-sectional transmission electron microscopy micrographs, high-density threading dislocations were found to be present in the initial growth areas, while the lateral overgrowth areas demonstrated substantially reduced TDD or even defect-free areas. Furthermore, the X-ray diffraction results showed that the films were fully relaxed and mostly pure Ge. Full relaxation and low TDD Ge films are two surprising results given that the growth occurred at a low temperature (375 °C), which cannot be understood with the current misfit dislocation nucleation and glide model of film relaxation. For these reasons, we suggest the presence of a new relaxation mechan...