Sn-enriched Ge/GeSn nanostructures grown by MBE on (001) GaAs and Si wafers

Abstract

Elastically stressed metastable GeSn layers with a tin molar fraction as large as 0.185 are grown on (001) Si and GaAs wafers covered with a germanium buffer layer. A set of wafers with a deviation angle in the range 0°-10° is used. It is established that the GeSn crystal undergoes monoclinic deformation with the angle β to 88° in addition to tetragonal deformation. Misorientation of the wafers surface results in increasing efficiency of the incorporation of tin adatoms into the GeSn crystal lattice. Phase separation in the solid solution upon postgrowth annealing of the structures begins long before the termination of plastic relaxation of elastic heteroepitaxial stresses. Tin released as a result of GeSn decomposition predominantly tends to be found on the surface of the sample. Manifestations of the brittle-plastic mechanism of the relaxation of stresses resulting in the occurrence of microcracks in the subsurface region of the structures under investigation are found.

Tensile-strained Ge1−x Sn x layers on Si(001) substrate by solid-phase epitaxy featuring seed layer introduction

“…Thus, the study of Ge 1−x Sn x epitaxial layers grown on substrates with smaller lattice constants, such as Ge or GaAs, and the applications of this material have rapidly progressed. [12][13][14] However, it is still necessary to achieve an enhancement of electron mobility in Ge 1−x Sn x , to decrease the effective mass of the L point and/or to enclose the L point to Γ point. 15) To this end, increasing the Sn content and applying tensile strain in Ge 1−x Sn x are important approaches.…”