Enhancement-mode buried strained silicon channel quantum dot with tunable lateral geometry

Abstract

We propose and demonstrate a relaxed-SiGe/strained-Si (SiGe/s-Si) enhancement-mode gate stack for quantum dots. The enhancement-mode SiGe/s-Si structure is pursued because it spaces the quantum dot away from charge and spin defect rich dielectric interfaces and minimizes background dopants. A mobility of 1.6\times10^5 cm^2/Vs at 5.8\times10^{11}/cm^2 is measured in Hall bars that witness the same device process flow as the quantum dot. Periodic Coulomb blockade (CB) is measured in a double-top-gated lateral quantum dot nanostructure. The CB terminates with open diamonds up to \pm 10 mV of DC voltage across the device. The devices were fabricated within a 150 mm Si foundry setting that uses implanted ohmics and chemical-vapor-deposited dielectrics, in contrast to previously demonstrated enhancement-mode SiGe/s-Si structures made with AuSb alloyed ohmics and atomic-layer-deposited dielectric. A modified implant, polysilicon formation and annealing conditions were utilized to minimize the thermal budget so that the buried s-Si layer would not be washed out by Ge/Si interdiffusion.

4 pages, 3 figures

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• Quantum Computation with Quantum Dots
• Spins in few-electron quantum dots
• Single-shot readout of an electron spin in silicon
• Electronic measurement and control of spin transport in Silicon
• Excitation Spectra of Circular Few-Electron Quantum Dots
• Electron Spin-Relaxation Times of Phosphorus Donors in Silicon
• Electron correlation in the second Landau level; a competition between many, nearly degenerate quantum phases
• Pulsed-gate measurements of the singlet-triplet relaxation time in a two-electron double quantum dot

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• Utilizing multimodal microscopy to reconstruct Si/SiGe interfacial atomic disorder and infer its impacts on qubit variability
• Stable quantum dots in an InSb two-dimensional electron gas
• Coherent electrical rotations of valley states in Si quantum dots using the phase of the valley-orbit coupling
• SiGe/Si quantum dot electron spin decoherence dependence on ${}^{73}$Ge
• Voltage controlled exchange energies of a two electron silicon double quantum dot with and without charge defects in the dielectric
• Fabrication of quantum dots in undoped Si/Si${}_{0.8}$Ge${}_{0.2}$ heterostructures using a single metal-gate layer