Artificial GeSi substrates for heteroepitaxy: Achievements and problems

Abstract

It is desirable to have a set of substrates which are based on Si and ensure growth of heterostructures with various lattice parameters in order to develop electronic devices composed of semiconductor materials whose epitaxial growth is reasonably well developed. Such substrates are typically referred to as artificial. In this paper, a comparative analysis of various methods for the fabrication of artificial substrates (heterostructures), in which the relaxation of stresses is based on the introduction of misfit dislocations, is performed. Based on published and new experimental data, the mechanisms for attaining a low density of threading dislocations in plastically relaxed films represented by heterostructures composed of GeSi and an Si buffer layer grown at low temperatures are analyzed. The problems and results of another group of methods for obtaining artificial substrates which gained favor recently and become known as “compliant” or “soft” substrates are discussed. The most important electrical parameters of Si and GeSi films grown on artificial substrates are considered.