Initial stage of the two-dimensional to three-dimensional transition of a strained SiGe layer on a pit-patterned Si(001) template

Abstract

We investigate the initial stage of the 2D-3D transition of strained Ge layers deposited on pit-patterned Si(001) templates. Within the pits, which assume the shape of inverted, truncated pyramids after optimized growth of a Si buffer layer, the Ge wetting layer develops a complex morphology consisting exclusively of {105} and (001) facets. These results are attributed to a strain-driven step-meandering instability on the facetted side-walls of the pits, and a step-bunching instability at the sharp concave intersections of these facets. Although both instabilities are strain-driven, their coexistence becomes mainly possible by the geometrical restrictions in the pits.It is shown that the morphological transformation of the pit surface into low-energy facets has strong influence on the preferential nucleation of Ge islands at the flat bottom of the pits. 81.16.Dn, PDF created with pdfFactory Pro trial version www.pdffactory.com

Collective Shape Oscillations of SiGe Islands on Pit-Patterned Si(001) Substrates: A Coherent-Growth Strategy Enabled by Self-Regulated Intermixing

“…First, the observation of such a phenomenon on pit-patterned substrates is easier with respect to flat substrates because the plastic relaxation is delayed. This is due to (i) the elastic-energy relaxation provided by the shallow pit filled with a Ge-poor SiGe alloy located below the island (a purely elastic effect) [15], (ii) the larger availability of Si flow from the faceted pit sidewalls which do not display a homogeneous wetting layer [27], and (iii) the effect of ordered pits in producing islands with very similar properties at all stages of growth. The latter prevents local composition and size fluctuations which are typical for growth on planar surfaces and are responsible for the occurrence of a few plastically relaxed islands even at relatively low Ge coverages [17].…”

SiGe growth on patterned Si(001) substrates: Surface evolution and evidence of modified island coarsening

“…11 However, the island formation and subsequent evolution on pit-patterned Si͑001͒ substrates are still not completely understood. While the initial stages of the twodimensional ͑2D͒ to 3D transition during Ge deposition on a pit-patterned Si͑001͒ surface have been recently studied, 12 a detailed investigation of the morphological changes occurring during island growth is still lacking.…”

Influence of composition and substrate miscut on the evolution of {105}-terminated in-plane Si1−xGex quantum wires on Si(001)

“…1(b), the 551 and 100 intersection lines differ substantially in their atomic configuration. 31 The hut clusters on Si(001) are therefore also different from the {105}-terminated SiGe wire bundles into which a Ge wetting layer on (1 1 10) oriented Si substrates disintegrates, 32,33 because their ridges are 551 oriented. Accordingly, the base angles of the triangular cross sections amount to 11.3…”

“…Simultaneously, we studied the influence of small substrate miscuts by employing a batch of 4 Si (001) The substrates were chemically pre-cleaned 37 and the residual oxide removed in 1% hydrofluoric acid before being loaded into a Riber Siva 45 MBE system. 32 The substrates were degassed in situ at 720…”