Reducing disorder in Ge quantum wells by using thick SiGe barriers

Abstract

We investigate the disorder properties of two-dimensional hole gases in Ge/SiGe heterostructures grown on Ge wafers, using thick SiGe barriers to mitigate the influence of the semiconductor-dielectric interface. Across several heterostructure field effect transistors we measure an average maximum mobility of $(4.4\pm 0.2)\times 10^6\mathrm{c}{\mathrm{m}}^2/Vs$ at a saturation density of $(1.72\pm 0.03)\times 10^{11}\mathrm{c}{\mathrm{m}}^{-2}$, corresponding to a long mean free path of $(30\pm 1)\mu \mathrm{m}$. The highest measured mobility is $4.68\times 10^6\mathrm{c}{\mathrm{m}}^2/Vs$. We identify uniform background impurities and interface roughness as the dominant scattering mechanisms limiting mobility in a representative device, and we evaluate a percolation-induced critical density of $(4.5\pm 0.1)\times 10^9\mathrm{c}{\mathrm{m}}^{-2}$. This low-disorder heterostructure, according to simulations, may support the electrostatic confinement of holes in gate-defined quantum dots.

References in corpus (9)

• The Observation of Percolation-Induced 2D Metal-Insulator Transition in a Si MOSFET
• Operating semiconductor quantum processors with hopping spins
• Atomic fluctuations lifting the energy degeneracy in Si/SiGe quantum dots
• Sweet-spot operation of a germanium hole spin qubit with highly anisotropic noise sensitivity
• Germanium wafers for strained quantum wells with low disorder
• Annealing shallow Si/SiO${}_2$ interface traps in electron-beam irradiated high-mobility metal-oxide-silicon transistors
• Mobility versus quality in 2D semiconductor structures
• Low disorder and high valley splitting in silicon
• Understanding disorder in Silicon quantum computing platforms: Scattering mechanisms in Si/SiGe quantum wells

Cited by in corpus (3)

• Exploiting epitaxial strained germanium for scaling low noise spin qubits at the micron-scale
• Superconducting Proximity Effect in Two-Dimensional Hole Gases
• Variability of hole spin qubits in planar Germanium