Alloying mechanisms for epitaxial nanocrystals

TL;DR

This paper investigates the various alloying mechanisms in epitaxial nanocrystals, analyzing how growth conditions and annealing environments influence intermixing, surface diffusion, and intra-island diffusion in Ge:Si islands.

Contribution

It provides a detailed analysis of the relative importance of different alloying mechanisms under various growth and annealing conditions.

Findings

Intermixing during growth decreases with faster growth rates.

Si surface diffusion dominates during H₂ annealing.

Ge surface diffusion and intra-island diffusion are prevalent during PH₃ annealing.

Abstract

The different mechanisms involved in the alloying of epitaxial nanocrystals are reported in this letter. Intermixing during growth, surface diffusion and intra-island diffusion were investigated by varying the growth conditions and annealing environments during chemical vapor deposition. The relative importance of each mechanism was evaluated in determining a particular composition profile for dome-shaped Ge:Si (001) islands. For samples grown at a faster rate, intermixing during growth was reduced. Si surface diffusion dominates during H$_2$ annealing whereas Ge surface diffusion and intra-island diffusion prevail during annealing in a PH$_3$ environment.