# Islanding, growth mode and ordering in Si heteroepitaxy on Ge(001) substrates structured by thermal annealing

## TL;DR

This study investigates how thermal annealing of nanostructured Ge substrates influences Si/Ge heteroepitaxial growth modes, islanding behavior, and spatial ordering, revealing substrate structure-dependent growth dynamics and site patterning.

## Contribution

It demonstrates how substrate misorientation and surface structure control growth modes, islanding critical thickness, and dot site ordering in Si heteroepitaxy on Ge(001).

## Key findings

- Lowered islanding critical thickness on highly-miscut Ge(001).
- Growth mode varies with surface domain structure.
- Substrate patterning influences dot site spatial correlation.

## Abstract

Si/Ge heteroepitaxial dots under tensile strain are grown on nanostructured Ge substrates produced by high-temperature flash heating exploiting the spontaneous faceting of the Ge(001) surface close to the onset of surface melting. A very diverse growth mode is obtained depending on the specific atomic structure and step density of nearby surface domains with different vicinal crystallographic orientations. On highly-miscut areas of the Ge(001) substrate, the critical thickness for islanding is lowered to about 5 ML, in contrast to the 11 ML reported for the flat Ge(001) surface, while on unreconstructed (1x1) domains the growth is Volmer-Weber driven. An explanation is proposed considering the diverse relative contributions of step and surface energies on misoriented substrates. In addition, we show that the bottom-up pattern of the substrate naturally formed by thermal annealing determines a spatial correlation for the dot sites.

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Source: https://tomesphere.com/paper/1902.01207