Intervalley coupling for interface-bound electrons in silicon: An effective mass study

Abstract

Orbital degeneracy of the electronic conduction band edge in silicon is a potential roadblock to the storage and manipulation of quantum information involving the electronic spin degree of freedom in this host material. This difficulty may be mitigated near an interface between Si and a barrier material, where intervalley scattering may couple states in the conduction ground state, leading to nondegenerate orbital ground and first excited states. The level splitting is experimentally found to have a strong sample dependence, varying by orders of magnitude for different interfaces and samples. The basic physical mechanisms leading to such coupling in different systems are addressed. We expand our recent study based on an effective mass approach, incorporating the full plane-wave expansions of the Bloch functions at the conduction band minima. Physical insights emerge naturally from a simple Si/barrier model. In particular, we present a clear comparison between ours and different approximations and formalisms adopted in the literature and establish the applicability of these approximations in different physical scenarios.

11 pages, 3 figures, 2 tables

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• Influence of sample momentum space features on scanning tunnelling microscope measurements
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• Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots
• Electronic Correlations in Multielectron Silicon Quantum Dots
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• Silicon Donor Array as a Disordered One-Dimensional Electron Gas
• Digital-Controlled Method of Conveyor-Belt Spin Shuttling in Silicon for Large-Scale Quantum Computation