Mechanism of stress relaxation in Ge nanocrystals embedded in SiO2

Abstract

Ion-beam-synthesized 74 Ge nanocrystals embedded in an amorphous silica matrix exhibit large compressive stresses in the as-grown state. The compressive stress is determined quantitatively by evaluating the Raman line shift referenced to the line position of freestanding nanocrystals. Post-growth thermal treatments lead to stress reduction. The stress relief process is shown to be governed by the diffusive flux of matrix atoms away from the local nanocrystal growth region. A theoretical model that quantitatively describes this process is presented.

Interfacial free energies determined from binary embedded alloy nanocluster geometry

“…• C. 16 This is consistent with observations of McGraw 17 and Belousov et al 18 showing a steep increase in elastic moduli of various glasses at temperatures below ∼580…”

“…GeAu BEANs are produced by implanting Ge into Au-doped silica films fabricated by co-sputtering Au and Si under a 90% Ar-10% O atmosphere onto Si(111) substrates. Specifically, for the GeAu case, 74 Ge is implanted using three energies, in order to obtain a more uniform compositions profile: 3.5 × 10 16 cm −2 at 150 keV, 4.7 × 10 15 cm…”

Fabrication and characteristics of porous germanium films

“…The effect of stress on Raman shift can be changed by stress relaxation using post-annealing [38][39][40]. For instance, the Raman peak of a Ge sample with compressive strain shifts to lower frequencies as the annealing time increases [32,41,42]. This phenomenon was also observed in this study.…”

Theory of Nanocluster Size Distributions from Ion Beam Synthesis

“…The deposition of energetic ions fragments the clusters, leads to inverse Ostwald ripening [9], and ultimately limits cluster sizes. The basic understanding of IBS has been exploited to fabricate interesting nanostructures [9][10][11][12][13][14][15] and alter cluster size distributions [15,16]. But unlike low dose semiconductor doping via implantation that is extensively studied and understood [17][18][19][20], no detailed, comprehensive, quantitative theory if IBS has been developed.…”