Magnetic-field dependence of valley splitting for Si quantum wells grown on tilted SiGe substrates

Abstract

The valley splitting of the first few Landau levels is calculated as a function of the magnetic field for electrons confined in a strained silicon quantum well grown on a tilted SiGe substrate, using a parameterized tight-binding method. For a zero substrate tilt angle, the valley splitting slightly decreases with increasing magnetic field. In contrast, the valley splitting for a finite substrate tilt angle exhibits a strong and non-monotonous dependence on the magnetic field strength. The valley splitting of the first Landau level shows an exponential increase followed by a slow saturation as the magnetic field strength increases. The valley splitting of the second and third Landau levels shows an oscillatory behavior. The non-monotonous dependence is explained by the phase variation of the Landau level wave function along the washboard-like interface between the tilted quantum well and the buffer material. The phase variation is the direct consequence of the misorientation between the crystal axis and the confinement direction of the quantum well. This result suggests that the magnitude of the valley splitting can be tuned by controlling the Landau-level filling factor through the magnetic field and the doping concentration.

References in corpus (8)

• Exchange in silicon-based quantum computer architecture
• Boundary conditions for the electronic structure of finite-extent, embedded semiconductor nanostructures
• Valley splitting in strained silicon quantum wells
• Valley Polarization in Si(100) at Zero Magnetic Field
• Strong enhancement of the valley splitting in a 2D electron system in silicon
• Valley splitting of Si/SiGe heterostructures in tilted magnetic fields
• Observation of Inter-Valley Gap Anomaly of Two Dimensional electrons in Silicon
• Manifestation of the Exchange Enhancement of the Valley Splitting in the Quantum Hall Effect Regime

Cited by in corpus (5)

• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• Intervalley coupling for interface-bound electrons in silicon: An effective mass study
• Theory of Single Electron Spin Relaxation in Si/SiGe Lateral Coupled Quantum Dots
• The critical role of substrate disorder in valley splitting in Si quantum wells
• Valley splitting in a Si/SiGe quantum point contact