Elastically Strain-Sharing Si(110) Nanomembranes

Abstract

Defect-free, smooth, tensilely strained Si(110) has been fabricated via elastic strain relaxation of trilayer Si/SiGe/Si(110) nanomembrane heterostructures grown on silicon-on-insulator (SOI), in which the middle layer is compressively strained. We release these trilayer structures via selective etching to allow elastic strain sharing between the Si/SiGe/Si(110) layers, thus creating tensilely strained Si(110). We use low-temperature molecular beam epitaxy (MBE) to grow the SiGe and top Si layers to create smooth films and incorporate more strain in the Si(110) layers; the low growth temperatures suppress relaxation, allowing for thicker SiGe(110) films. The strain in the Si(110) layers can be controlled with elastic strain engineering up to ~0.7%.