Cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at milli-Kelvin temperatures

Abstract

Silicon can be isotopically enriched, allowing for the fabrication of highly coherent semiconductor spin qubits. However, the conduction band of bulk Si exhibits a six-fold valley degeneracy, which may adversely impact the performance of silicon quantum devices. To date, the spatial characterization of valley states in Si remains limited. Moreover, techniques for probing valley states in functional electronic devices are needed. We describe here a cryogen-free scanning gate microscope for the characterization of Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices at mK temperatures. The microscope is based on the Pan-walker design, with coarse positioning piezo stacks and a fine scanning piezo tube. A tungsten microscope tip is attached to a tuning fork for active control of the tip-to-sample distance. To reduce vibration noise from the pulse tube cooler, we utilize both active and passive vibration isolation mechanisms, and achieve a root-mean-square noise in $z$ of $\sim$ 2 nm. Our microscope is designed to characterize fully functioning Si/Si${}_{0.7}$Ge${}_{0.3}$ quantum devices. As a proof of concept, we use the microscope to manipulate the charge occupation of a Si quantum dot, opening up a range of possibilities for the exploration of quantum devices and materials.

References in corpus (9)

• Scalable gate architecture for densely packed semiconductor spin qubits
• A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots
• Measurement of valley splitting in high-symmetry Si/SiGe quantum dots
• Magnetic field dependence of valley splitting in realistic Si/SiGe quantum wells
• Site-selective quantum control in an isotopically enriched 28Si/SiGe quadruple quantum dot
• Valley splittings in Si/SiGe quantum dots with a germanium spike in the silicon well
• Detuning Axis Pulsed Spectroscopy of Valley-Orbital States in Si/SiGe Quantum Dots
• Force-gradient-induced mechanical dissipation of quartz tuning fork force sensors used in atomic force microscopy
• Probing the Spatial Variation of the Inter-Valley Tunnel Coupling in a Silicon Triple Quantum Dot

Cited by in corpus (8)

• Practical Strategies for Enhancing the Valley Splitting in Si/SiGe Quantum Wells
• Strategies for enhancing spin-shuttling fidelities in Si/SiGe quantum wells with random-alloy disorder
• Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum dot
• In-situ scanning gate imaging of individual two-level material defects in live superconducting quantum circuits
• Dispersive readout of a silicon quantum device using an atomic force microscope-based rf gate sensor
• Second Quantization: Gating a Quantum Dot Through the Sequential Removal of Single Electrons from a Nanoscale Floating Gate
• The effects of alloy disorder on strongly-driven flopping mode qubits in Si/SiGe
• Towards Utilizing Scanning Gate Microscopy as a High-Resolution Probe of Valley Splitting in Si/SiGe Heterostructures