Valley splitting in strained silicon quantum wells

By Timothy B. Boykin, Gerhard Klimeck, M. Eriksson, M. Friesen, Susan N. Coppersmith, Paul von Allmen, F. Oyafuso, Seungwon Lee. 2003

150 citations recorded by the source corpus.

A theory based on localized-orbital approaches is developed to describe the valley splitting observed in silicon quantum wells. The theory is appropriate in the limit of low electron density and relevant for quantum computing architectures. The valley splitting is computed for realistic devices using the quantitative nanoelectronic modeling tool NEMO. A simple, analytically solvable tight-binding model reproduces the behavior of the splitting in the NEMO results and yields much physical insight. The splitting is in general nonzero even in the absence of electric field in contrast to previous works. The splitting in a square well oscillates as a function of S, the number of layers in the quantum well, with a period that is determined by the location of the valley minimum in the Brillouin zone. The envelope of the splitting decays as S−3. The feasibility of observing such oscillations experimentally in Si/SiGe heterostructures is discussed.

Subfields: Atomic and Molecular Physics, and Optics, Electrical and Electronic Engineering

View Paper: https://www.semanticscholar.org/paper/5e3504cad027b30b3e9404e4c8a2929c8fd3eaa8

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In Atomic and Molecular Physics, and Optics

In Electrical and Electronic Engineering

Citations in the corpus

Controllable valley splitting in silicon quantum devices (2006, background): “In principle, sharp confinement potentials, like the quantum well interfaces, couple these two valleys and lift the degeneracy, providing a unique ground state if the coupling is strong enough [14, 15].”
Electronic properties of silicon nanowires (2005, background): “4(c) is a two-dimensional analogue of the splitting recently investigated in planar Si quantum wells [40].”
On the validity of the parabolic effective-mass approximation for the I-V calculation of silicon nanowire transistors (2004, background): “The splitting energy is seen to fluctuate as a function of the number of atomic layers and the envelope decreases with the wire width according to , analogous with the band splitting observed in Si quantum wells [ 18 ]‐[20].”
Materials challenges and opportunities for quantum computing hardware (2021, background): “This interface is engineered through strain, confinement, and electric fields to lift the valley degeneracy, which is crucial for achieving long coherence times (185) and ensuring spin-tocharge conversion efficiency (186).”
Silicon quantum electronics (2012, background): “…parameter that is fit to tight-binding results, as the output of a multiscale approach (Chutia et al., 2008; Saraiva et al., 2009), or by explicit atomistic calculation on large scales, as embodied by the NEMO tool suite (Boykin et al., 2004b; Klimeck et al., 2007, 2002; Steiger et al., 2011).”