Valley Splitting in Si Quantum Dot Structures

November 21, 2007

Blogging on Peer-Reviewed Research

Silicon has an indirect bandgap, which means that a conduction electron has six choices (+/- x,y,z) for where to go. Real quantum dot structures are finite, which splits off most of these “valleys”, so that there are typically only two low-lying ones to contend with, and strain and other interfacial effects typically remove the remaining degeneracy. However, the split is often small, and transitions between the dimensions often contend with the transitions we want to make happen in the quantum structures.

People are starting to do atomistic modeling to get a handle on that actual features that lead to valley splitting. This paper is a very good overview, and the authors have written a number of other papers along the same lines.

The seminal review paper is Ando’s 1984 RMP review, which is a whopping 236 pages. Most of the effects are summarized in his (much shorter and much more approachable) 1979 PRB paper.


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