Electronic devices in nuclear-spin free germanium heterostructures

Hole spin qubits are a promising platform for quantum computation, due to strong spin-orbit coupling allowing electrical qubit control. The p-symmetry in the hole wavefunction suppresses decoherence arising from hole-nuclear interactions, and experimental signatures of nuclear spin induced decoherence have been reported. Nuclear spin depleted 70Ge/28Si70Ge heterostructures are promising materials for realizing longer spin coherence times, but heterostructures with the required purity have not been available, to date. Here we present magnetotransport characterization of nuclear-spin-free Ge heterostructures on gated Hallbars, at hole concentrations between 0.7 × 10¹¹ cm⁻² to 1.25 × 10¹¹ cm⁻². We find a peak mobility of up to 220,000 cm²/Vs at a concentration of 1 × 10¹¹ cm⁻². We also discuss the effective hole masses in these heterostructures along with a comprehensive study of quantum scattering times. We present preliminary results on characterization of quantum dot devices fabricated in the 70Ge/28Si70Ge heterostructures.