Valley-Free Silicon Fins Caused by Shear Strain

Abstract

Electron spins confined in silicon quantum dots are promising candidates for large-scale quantum computers. However, the degeneracy of the conduction band of bulk silicon introduces additional levels dangerously close to the window of computational energies, where the quantum information can leak. The energy of the valley states -- typically 0.1 meV -- depends on hardly controllable atomistic disorder and still constitutes a fundamental limit to the scalability of these architectures. In this work, we introduce designs of complementary metal-oxide-semiconductor (CMOS)-compatible silicon fin field-effect transistors that enhance the energy gap to noncomputational states by more than one order of magnitude. Our devices comprise realistic silicon-germanium nanostructures with a large shear strain, where troublesome valley degrees of freedom are completely removed. The energy of noncomputational states is therefore not affected by unavoidable atomistic disorder and can further be tuned in situ by applied electric fields. Our design ideas are directly applicable to a variety of setups and will offer a blueprint toward silicon-based large-scale quantum processors.

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Cited by in corpus (8)

• Strategies for enhancing spin-shuttling fidelities in Si/SiGe quantum wells with random-alloy disorder
• Coupling conduction-band valleys in SiGe heterostructures via shear strain and Ge concentration oscillations
• Theory of Valley Splitting in Si/SiGe Spin-Qubits: Interplay of Strain, Resonances and Random Alloy Disorder
• Valley splitting by extended zone effective mass approximation incorporating strain in silicon
• Fabrication, characterization and mechanical loading of Si/SiGe membranes for spin qubit devices
• Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots
• Effects of valley splitting on resonant-tunneling readout of spin qubits
• Wide Electrical Tunability of the Valley Splitting in a Doubly gated Silicon-on-Insulator Quantum Well