Evidence for Kinetic Limitations as a Controlling Factor of Ge Pyramid Formation: a Study of Structural Features of Ge/Si(001) Wetting Layer Formed by Ge Deposition at Room Temperature Followed by Annealing at 600 {\deg}C

TL;DR

This study investigates whether Ge quantum dot arrays on Si(001) are formed through equilibrium or kinetic processes, finding that pyramid formation is kinetically controlled while the wetting layer is an equilibrium structure.

Contribution

It provides experimental evidence that Ge pyramid formation on Si(001) is kinetically limited, contrasting with the equilibrium nature of the wetting layer.

Findings

Ge/Si(001) film consists of wetting layer and large Ge clusters after annealing.

Pyramid formation is kinetically controlled, not equilibrium.

Wetting layer is confirmed as an equilibrium structure.

Abstract

The article presents an experimental study of an issue of whether the formation of arrays of Ge quantum dots on the Si(001) surface is an equilibrium process or it is kinetically controlled. We deposited Ge on Si(001) at the room temperature and explored crystallization of the disordered Ge film as a result of annealing at 600 {\deg}C. The experiment has demonstrated that the Ge/Si(001) film formed in the conditions of an isolated system consists of the standard patched wetting layer and large droplike clusters of Ge rather than of huts or domes which appear when a film is grown in a flux of Ge atoms arriving on its surface. We conclude that the growth of the pyramids appearing at temperatures greater than 600 {\deg}C is controlled by kinetics rather than thermodynamic equilibrium whereas the wetting layer is an equilibrium structure.