Epitaxial growth of InAs/GaAs quantum dots on {113}-faceted Ge/Si (001) hollow substrate

Abstract

The direct epitaxial growth of GaAs on Si suffers from their nature of lattice mismatch, thermal mismatch and polarity difference induced anti-phase domains (APDs). Here, we report the high quality and thin GaAs film grown on {113}-faceted Ge/Si (001) hollow substrate by in-situ hybrid molecular beam epitaxy. By directly growth of Ge on U-shape patterned Si (001), a strain-relaxed high-quality Ge sawtooth hollow structure with {113} facets was obtained. With an additional 400 nm GaAs deposition, an APD-free surface with a root-mean-square roughness of merely 0.67 nm is obtained on such Ge {113} /Si (001) substrate. The lattice mismatch dislocation between Ge and Si is found to terminate mostly at the sidewalls of the hollow structures. The {113}-faceted Ge surface is acting as an equivalent to the miscut substrate, which annihilates the APDs at the GaAs/Ge interface. High-resolution X-ray diffraction characterization reveals that the hollow structures can effectively reduce the thermal strain, leading to a crack-free GaAs film up to 7 µm. Five-layer InAs/GaAs quantum dots (QDs) on such virtual GaAs/Ge {113} /Si (001) substrate without any dislocation filter layers exhibits almost the same photoluminescence (PL) intensity as that on the GaAs substrate, providing a promising method for integrating III-V QD lasers with silicon photonic platform.