Strain field imaging on Si/SiGe(001)-(2×1) surfaces by low-energy electron microscopy and scanning tunneling microscopy

Abstract

We show that ultrahigh-vacuum low-energy electron microscopy and scanning tunneling microscopy can be used to image residual uniaxial strain fields on (001) surfaces of SiGe heterostructures. We find that the surface crosshatch morphology on these films is highly correlated with large spatial variations in the residual uniaxial strain fields, confirming the importance of local strain fields in the formation of crosshatch.

Inhomogeneous distribution of dislocations in a SiGe graded layer and its influence on surface morphology and misfit dislocations at the interface of strained Si∕Si0.8Ge0.2

“…Therefore, most of the H regions were correlated with the surface ridges. This indicates that the growth rate was significantly affected by the underlying dislocations, as first proposed by Fitzgerald et al 10,11 The growth rate was locally enhanced at the strain relaxed surface above the H regions, because the H regions led to much more strain relaxation than the relatively low dislocation density regions. 12 On the other hand, the EBIC dark bands had a larger spatial spacing than the surface fine lines.…”

Effect of Anisotropic Strain on the Crosshatch Electrical Activity in Relaxed GeSi Films

“…No additional dislocations nucleate in the 1 mm uniform Ge 0.3 Si 0.7 cap layer [8]. Strain fields from the underlying misfit dislocations affect the local growth rate, resulting in nonperiodic surface undulations (crosshatch) [1,9]. These samples have been comprehensively described elsewhere [1,5,8].…”

“…Strain fields have been shown to be associated with crosshatch [1,4,9,14]. Their presence affects local band structure, resulting in index and/or absorption variation.…”