Electron spin coherence of shallow donors in natural and isotopically enriched germanium

Abstract

Germanium is a widely used material for electronic and optoelectronic devices and recently it has become an important material for spintronics and quantum computing applications. Donor spins in silicon have been shown to support very long coherence times ($T_2$) when the host material is isotopically enriched to remove any magnetic nuclei. Germanium also has non-magnetic isotopes so it is expected to support long $T_2$s while offering some new properties. Compared to Si, Ge has a strong spin-orbit coupling, large electron wavefunction, high mobility, and highly anisotropic conduction band valleys which will all give rise to new physics. In this Letter, the first pulsed electron spin resonance (ESR) measurements of $T_2$ and the spin-lattice relaxation ($T_1$) times for ${}^{75}$As and ${}^{31}$P donors in natural and isotopically enriched germanium are presented. We compare samples with various levels of isotopic enrichment and find that spectral diffusion due to ${}^{73}$Ge nuclear spins limits the coherence in samples with significant amounts of ${}^{73}$Ge. For the most highly enriched samples, we find that $T_1$ limits $T_2$ to $T_2=2T_1$. We report an anisotropy in $T_1$ and the ensemble linewidths for magnetic fields oriented along different crystal axes but do not resolve any angular dependence to the spectral-diffusion-limited $T_2$ in samples with ${}^{73}$Ge.

References in corpus (11)

• Electron Spin Resonance Transistors for Quantum Computing in Silicon-Germanium Heterostructures
• Electron spin coherence exceeding seconds in high purity silicon
• Atomic clock transitions in silicon-based spin qubits
• Theory of nuclear induced spectral diffusion: Spin decoherence of phosphorus donors in Si and GaAs quantum dots
• Line Broadening and Decoherence of Electron Spins in Phosphorus-Doped Silicon Due to Environmental 29^Si Nuclear Spins
• An experimental demonstration of room-temperature spin transport in n-type Germanium epilayers
• Gate induced g-factor control and dimensional transition for donors in multi-valley semiconductors
• Anisotropy-driven spin relaxation in germanium
• Isotope effect on electron paramagnetic resonance of boron acceptors in silicon
• Isotopic disorder in Ge single crystals probed with 73Ge NMR
• SiGe/Si quantum dot electron spin decoherence dependence on ${}^{73}$Ge

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• Exchange interaction of hole-spin qubits in double quantum dots in highly anisotropic semiconductors
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• A two-dimensional 10-qubit array in germanium with robust and localised qubit control
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• Donors in Ge as Qubits: Establishing Physical Attributes
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