Tight binding studies of strained Ge/Si(001) growth

TL;DR

This paper uses tight binding calculations to analyze the energetics and geometries of strained Ge/Si(001) growth, explaining experimental phenomena such as surface reconstructions and trench formations.

Contribution

It extends previous models to multiple Ge layers, providing detailed explanations for observed surface effects during growth.

Findings

Good agreement with experimental observations

Reveals energetics behind trench and reconstruction formation

Extends understanding of multilayer Ge growth on Si(001)

Abstract

Experimental observations of the growth of more than one monolayer of Ge on Si(001) show a progression of effects beyond the (2xN) reconstruction which is seen at submonolayer coverages: a reduction in the value of N with coverage; formation of straight trenches of missing dimer vacancies; and formation of the (MxN) ``patch'' structure. We present tight binding calculations which investigate the energetics and geometries associated with these effects, and extend our earlier treatment of formation energies for reconstructions with different stoichiometries to the case of several layers of Ge. The results provide explanations for the various effects seen, and are in good agreement with experimental observations.