High-quality Ge film grown on Si substrate and its thermodynamic mechanism

Abstract

By right of the prominent properties, Ge film grown on Si substrate plays an important role in the field of optoelectronic devices. However, the dislocation density of Ge film grown on Si substrate is still high due to the relatively large lattice mismatch between Ge and Si of ~4.18% that hinders the further development of devices. In this work, high-quality Ge film grown on Si substrate has been obtained based on study of the thermodynamic mechanism. On the one hand, the thermodynamic mechanism of Ge film on Si substrate by First-principle calculation based on density functional theory; and then high-quality Ge films were achieved on Si substrate by the low temperature and high temperature two-step growth technique by molecular beam epitaxy accordingly. The as-grown 2.0 μm-thick Ge film show high quality with a full-width at half-maximums for Ge(004) of 110 arcsec and very smooth surface with a root-mean-square roughness of 0.2 nm. The Ge film achieved in this work is a promising candidate for the fabrication of optoelectronic devices.