INVESTIGATION OF POSSIBILITY OF THE MISFIT DISLOCATION DENSITY REDUCTION IN GE/SI FILMS WITH A BUFFER LAYER

Abstract

The possibility of improving the quality of Ge/Si heteroepitaxial structures with a buffer layer is investigated. It is shown that when using a preparatory layer consisting of nanostructures overgrown with a low-temperature buffer layer, it is possible to manifest the so-called effect of annihilation of the misfit dislocations in the bulk of the buffer layer Buf, which significantly improves the quality of the resulting structures. The dependence of the morphology of the surface of the pure Ge layer on the buffer on the growth time of nanostructures in the Si/Buf interface is presented. The optimal technological parameters of the growth of nanostructures for obtaining a Ge layer with a minimum roughness value are revealed. The best results were achieved when the deposition time of nanostructures was 2 min. At the same time, the minimum surface roughness value of 78 nm was achieved. It is shown that with a further increase in the size of the nanostructures, the process of annihilation of defects slows down, and the growth of the low-temperature buffer layer is replaced by a three-dimensional island growth, which increases the differences in the relief of the surface of the grown layer.

Keywords

• heteroepitaxy
• molecular beam epitaxy
• misfit dislocations
• buffer layer
• defect annihilation