Ge dots and nanostructures grown epitaxially on Si

Abstract

We review recent progress in the growth and characterization ofSi1−xGex islands and Ge dots on (001) Si. We discuss the evolution of the island morphology withSi1−xGex coverage, and the effect of growth parameters or post-growth annealing on the shape ofislands and dots. We outline some of the structural, vibrational, and optical properties ofSi1−xGex islands and review recent advances in the determination of their compositionand strain distribution. In particular, we present an analytical electrontransmission microscopy study of the Ge spatial distribution in Ge dots andSi /Si1−xGex island superlattices grown by molecular beam epitaxy and ultra-highvacuum chemical vapour deposition. We describe the use of undulatedSi1−xGex island superlattices for infrared detection at telecommunication wavelengths.Finally, we discuss various approaches currently being investigated to engineerSi1−xGex quantum dots and, in particular, control their size, density, and spatial distribution. Asexamples, we show how C pre-deposition on Si(001) can influence nucleation and growth ofGe islands and how low temperature Si homo-epitaxy can lead to a particular surface cuspmorphology that may promote dot nucleation.