Ge clusters and wetting layers forming from granular films on the Si(001) surface

TL;DR

This study investigates how rapid heating and annealing transform granular Ge films on Si(001) into wetting layers and clusters, revealing size evolution and surface reconstruction changes.

Contribution

It provides new insights into the morphological evolution and surface reconstruction of Ge films on Si(001) during thermal treatments.

Findings

Granular films transform into wetting layers and clusters after short-term annealing.

Long-term annealing causes cluster size increase and density decrease.

Surface reconstruction shifts to a thermodynamically favored c(4 x 2) pattern.

Abstract

The report studies transformation of a Ge granular film deposited at room temperature on the Si(001) surface to the Ge/Si(001) heterostructure as a result of rapid heating and annealing at 600C. As a result of the short-term annealing at 600C in conditions of a closed system, the Ge granular film transforms to the usual wetting layer and Ge clusters with multimodal size distribution and the Ge oval drops having the highest number density. After the long-term thermal treatment of the Ge film at the same temperature, Ge drops disappear; the large clusters increase their sizes at the expense of the smaller ones. The total density of Ge clusters on the surface drastically decreases. The wetting layer mixed c(4 x 2) + p(2 x 2) reconstruction transforms to the single c(4 x 2) one which is likely thermodynamically favoured. Pyramids or domes are not observed on the surface after any annealing.