Studies of SiGe alloy surfaces after reactive ion etching

Abstract

Reactive ion etching characteristics of epitaxial Si1−xGex layers in SiCl4/Cl2/N2 plasma are investigated by different diagnostic techniques, such as Auger electron spectroscopy, X‐ray photoelectron spectroscopy, and atomic force microscopy. Surface morphology and stoichiometry are influenced by the dry etching process. A slight Ge enrichment at the etched SiGe films is explained by the different volatility of the corresponding chlorides. Moreover, a procedure which allows an exactly determined etch stop in a thin buried SiGe alloy — as a necessary requirement for the following surface analysis — is introduced.

Elastic relaxation of dry-etched Si/SiGe quantum dots

“…However, analysis of the dot results requires some care because of two factors: First, the samples are incompletely etched through leaving at least one two-dimensional superlattice alloy layer and second, segregated Ge during dry etching recombines with the surface materials forming a diluted SiGe layer coating the entire structure. 7,12,28 Evidence for this comes from the Raman spectrum shown in Fig. 7͑c͒, which is taken from the unmasked and etched surface area in between the four arrays of dots on the sample.…”