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News on an old donor: Manipulation and detection of the spin states of phosphorus in silicon


One of the proposed solid-state realizations of quantum computing is based on the electronic and nuclear spins of phosphorous donors in silicon. The strong Kohn-Luttinger oscillations of the donor wave function in the indirect bandgap semiconductor Si, which complicate the exchange interaction of neighboring 31 P donors, can be suppressed by using strained silicon layers. Additionally, the strain will also affect the wave function at the donor atom, which can be observed directly via the hyperfine interaction between the donor electron and its nucleus in electron spin resonance. In this talk, I will present the results of detailed experimental and theoretical investigations of the hyperfine interaction by electrically detected magnetic resonance (EDMR), using the spin dependent 31 P-P b0 recombination as a spin-to-charge transfer. Furthermore, experiments studying the sensitivity limit of this detection mechanism will be summarized showing that as few as 50 P donors can already be resolved in nano-structured devices.

Beside the principal detection of phosphorus donors in silicon using EDMR, I discuss the observation of Rabi oscillations by investigating the current transient after the application of a microwave pulse which allows to read out the spin state of the electron. Pulsed EDMR experiments can be extended to Hahn echo tomography which allows to determine the T 2 time of the specific spin-to-charge transfer system used.