Simulating electron densities obtained in scanning gate microscopy of Si/SiGe quantum dot devices

Silicon-based quantum devices are a serious contender for scalable quantum computing, enabling coherent and highly controllable semiconductor spin qubits [1]. However, the six-fold “valley-degeneracy” of bulk Si [2] poses a challenge to silicon-based spin qubits [3]. Progress in understanding what limits valley splitting has been limited by the lack of high throughput measurements, calling for the development of new measurement techniques. A cryogen-free scanning gate microscope (SGM), compatible with Si/Si_0.7Ge_0.3 quantum dot devices and operating at milli-Kelvin temperatures, was recently demonstrated [4]. The microscope has the potential to enable spatial mapping of the valley splitting in silicon-based quantum dot devices. Here, we report recent efforts on quantum dot device simulations to investigate the influence of the tip bias in a SGM on the electronic occupation of a Si/SiGe quantum dot.

[1] Yoneda et al., Nature Nano. 13, 102 (2018)

[2] Zwanenburg et al., Rev. Mod. Phys. 85, 961 (2013)

[3] Friesen et al., Phys. Rev. B 81, 115324 (2010)

[4] Oh et al., arXiv:2105.05684