Remarkable Strength Characteristics of Defect-Free SiGe/Si Heterostructures Obtained by Ge Condensation

Abstract

International audienceWe compare the morphological and structural features of SiGe membranes fabricated by three different processes: direct deposition of Si0.5Ge0.5 on. Si(001) nominal substrate, direct deposition Of Si0.5Ge0.5 on silicon on insulator, and deposition of SiGe with low Ge concentration on silicon on insulator followed by Ge enrichment by condensation. We show that the formation of fully strained Ge-rich layers free of defects with a flat surface is possible only by the two-step epitaxy-condensation process. We demonstrate that the condensation based process enables the total inhibition of the morphological instability, together with the hindering of dislocations for critical thickness much greater than those commonly obtained by direct deposition. Those behaviors could be explained by the injection of self-interstitials in the Ge-rich layers during condensation. Such remarkable properties systems using a similar condensation process. could be generalized to many other systems using a similar condensation process

Raman microscopy and infrared optical properties of SiGe Mie resonators formed on SiO2 via Ge condensation and solid state dewetting

“…4. The Ge content appeared to be close to the expected one from the fabrication process [25][26][27][28] . The compressive strain in all three SiGe layers is quite strong up to ∼-0.027 for the partially condensed layer 3).…”

“…One set of UT-SGOI substrates was obtained by following a well-established procedure [25][26][27][28] . In Fig.…”

New Strategies for Engineering Tensile Strained Si Layers for Novel n-Type MOSFET

“…oxidation, dislocation nucleation is easily promoted, − together with the buckling of Si 1– x Ge x layers due to the viscous flow of oxides surrounding the Si 1– x Ge x layers . We reported recently that fully strained and free of dislocations Ge-rich layers (GRL) with a flat surface and abrupt interface can be fabricated using low-temperature condensation. , In these experimental conditions, the basic mechanism of GRL formation is a self-limited interdiffusion process regulated by the entropic term of the formation energy, which is a minimum at Si 0.5 Ge 0.5 at the expense of the elasticity driven interdiffusion. The process developed provides an easy and efficient way to produce planar GRLs with remarkable elastic features.…”

“…37 We reported recently that fully strained and free of dislocations Ge-rich layers (GRL) with a flat surface and abrupt interface can be fabricated using lowtemperature condensation. 38,39 In these experimental conditions, the basic mechanism of GRL formation is a self-limited interdiffusion process regulated by the entropic term of the formation energy, which is a minimum at Si 0.5 Ge 0.5 at the expense of the elasticity driven interdiffusion. The process developed provides an easy and efficient way to produce planar GRLs with remarkable elastic features.…”

“…Ge concentration is about 40% (lower than the 50% concentration obtained at temperatures <800 °C) and has a diffuse interface with the Si layer as already observed in the literature. 38,39 There is no relaxation and no dislocations in the layers.…”