Nucleation-vs-instability race in strained lms

Kailang Liu (1) , Isabelle Berbezier (2) , Thomas David , Luc Favre , Marco Abbarchi (2) , Antoine Ronda (2) , Peter Voorhees , Jean-Noël Aqua (3)

1 INSP - Institut des Nanosciences de Paris
2 IM2NP - Institut des Matériaux, de Microélectronique et des Nanosciences de Provence
3 IRPHE - Institut de Recherche sur les Phénomènes Hors Equilibre

Under the generic term Stranski-Krastanov are grouped two dierent growth mechanisms of SiGe quantum dots. They result from a self-organized Asaro-Tiller-Grinfel'd (ATG) instability at low strain, while at high strain, from a stochastic nucleation. We elucidate here the puzzling dierence between these two pathways thanks to a joint theoretical and experimental work. Nucleation is described within the master equation framework. By comparing the nucleation time scale and ATG characteristic time, we show that the former exhibits a strong exponential divergence at low strain while the latter behaves only algebraically. Consequently, at high/low strain, nucleation/instability occurs faster and inhibits the alternate evolution. The cross-over between the nu-cleation and ATG instability is found to occur both experimentally and theoretically at a Ge composition around 50%

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Kailang Liu, Isabelle Berbezier, Thomas David, Luc Favre, Marco Abbarchi, et al.. Nucleation-vs-instability race in strained lms. Physical Review Materials, 2017. ⟨hal-01788623⟩