On atomic structure of Ge huts growing on the Ge/Si(001) wetting layer

Abstract

Structural models of growing Ge hut clusters---pyramids and wedges---are proposed on the basis of data of recent STM investigations of nucleation and growth of Ge huts on the Si(001) surface in the process of molecular beam epitaxy. It is shown that extension of a hut base along <110> directions goes non-uniformly during the cluster growth regardless of its shape. Growing pyramids, starting from the second monolayer, pass through cyclic formation of slightly asymmetrical and symmetrical clusters, with symmetrical ones appearing after addition of every fourth terrace. We suppose that only symmetrical configurations of pyramids composed by 2, 6, 10, 14, etc. monolayers over the wetting layer are stable. This might explain less stability of pyramids in comparison with wedges in dense arrays obtained at low Ge deposition temperatures. Possible nucleation processes of pyramids and wedges on wetting layer patches from identical embryos composed by 8 dimers through formation of 1 monolayer high 16-dimer nuclei different only in their symmetry is discussed. Schematics of these processes are presented for both species of huts. It is concluded from precise STM measurements that top layers of WL patches are relaxed when huts nucleate on them.

20 pages, 9 figures

References in corpus (5)

• Monolithic growth of ultra-thin Ge nanowires on Si(001)
• CMOS compatible dense arrays of Ge quantum dots on the Si(001) surface: Hut cluster nucleation, atomic structure, and array life cycle during UHV MBE growth
• Phase transition on the Si(001) clean surface prepared in UHV MBE chamber: A study by high resolution STM and in situ RHEED
• An initial phase of Ge hut array formation at low temperature on Si(001)
• Ge/Si(001) heterostructures with dense arrays of Ge quantum dots: morphology, defects, photo-emf spectra and terahertz conductivity

Cited by in corpus (5)

• 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 °C
• Peculiarities and evolution of Raman spectra of multilayer Ge/Si(001) heterostructures containing arrays of low-temperature MBE-grown Ge quantum dots of different size and number density: Experimental studies and numerical simulations
• The formation of intermediate layers in covered Ge/Si heterostructures with low-temperature quantum dots: a study using high-resolution transmission electron microscopy and Raman spectroscopy
• Evolution of Ge wetting layers growing on smooth and rough Si (001) surfaces: isolated {105} facets as a kinetic factor of stress relaxation
• Ge clusters and wetting layers forming from granular films on the Si(001) surface