Valley splitting in a Si/SiGe quantum point contact

Abstract

We present the theory and measurement of valley splitting in a quantum point contact (QPC) in a modulation doped Si/SiGe heterostructure. Our measurements are performed on a submicron Schottky-gated device. An effective mass theory is developed for a QPC formed in a quantum well, grown on a miscut substrate. Both theory and experiments include a perpendicular magnetic field. Our results indicate that both QPC and magnetic confinement can enhance the valley splitting by reducing the spatial extent of the electronic wavefunction. Consequently, the valley splitting can be much larger than the spin splitting for small magnetic fields. We also observe different valley splittings for different transverse modes in the QPC, supporting the notion that when steps are present at the quantum well interface, the spatial extent of the wavefunction plays a dominant role in determining the valley splitting.

23 pages, 14 figures

References in corpus (24)

• Single-shot read-out of an individual electron spin in a quantum dot
• Driven coherent oscillations of a single electron spin in a quantum dot
• Coherent control of a single electron spin with electric fields
• Electrically driven single electron spin resonance in a slanting Zeeman field
• Rapid Single-Shot Measurement of a Singlet-Triplet Qubit
• Suppressing Spin Qubit Dephasing by Nuclear State Preparation
• Controllable valley splitting in silicon quantum devices
• Spin-echo of a single electron spin in a quantum dot
• Valley Splitting Theory of SiGe/Si/SiGe Quantum Wells
• Valley Polarization in Si(100) at Zero Magnetic Field
• Pauli-Spin-Blockade Transport through a Silicon Double Quantum Dot
• Theory of valley-orbit coupling in a Si/SiGe quantum dot
• Charge sensing and controllable tunnel coupling in a Si/SiGe double quantum dot
• Architecture for high-sensitivity single-shot readout and control of the electron spin of individual donors in silicon
• Spin states of the first four holes in a silicon nanowire quantum dot
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• Electric field effect on electron spin splitting in SiGe/Si quantum wells
• Single-electron quantum dot in Si/SiGe with integrated charge-sensing
• Enhancement mode double top gated MOS nanostructures with tunable lateral geometry
• Coulomb blockade and Kondo effect in a few-electron silicon/silicon-germanium quantum dot
• Charge sensing in enhancement mode double-top-gated metal-oxide-semiconductor quantum dots
• Valley splitting of Si/SiGe heterostructures in tilted magnetic fields
• Conductance quantization in etched Si/SiGe quantum point contacts
• Magnetic-field dependence of valley splitting for Si quantum wells grown on tilted SiGe substrates

Cited by in corpus (7)

• Silicon Quantum Electronics
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Valley subband splitting in bilayer graphene quantum point contact
• Theory of Single Electron Spin Relaxation in Si/SiGe Lateral Coupled Quantum Dots
• Transmission spectra and valley processing of graphene and carbon nanotube superlattices with inter-valley coupling
• Effects of Interface Disorder on Valley Splitting in SiGe/Si/SiGe Quantum Wells
• Resonant tunneling spectroscopy of valley eigenstates on a hybrid double quantum dot