Valley Splitting in Si/SiGe Quantum Dots

Abstract

Quantum computation (QC) represents a potentially revolutionary advancement to computer science. Quantum superposition will allow us to solve certain complicated problems in polynomial time. However, physical realization of a quantum computer must be robust enough to maintain quantum states from one clock cycle to the next. Spins in silicon quantum dots are an attractive candidate for QC due to a weak hyper ne interaction, but present the challenge of a six-fold degenerate conduction band. In the presence of uniaxial strain, this six-fold degeneracy is split into a higher quartet and a lower doublet. This thesis examines the splitting of the lower doublet. We use effective mass theory to develop a simulation scheme to determine where the optimum valley splitting values would be given an image of the atomic interface. We use simulation software to mimic device operation, and then use these results with our e ective mass-based simulation to calculate where accumulation mode gate placement would result in the highest splitting values. Results show that the interface places a large role in optimizing gate placement, and that latter interface regions result in the highest splitting values