Intraband Spin-Dependent Recombination of Bound Holes in Silicon

We generate paramagnetic centers on a heavily boron-doped Si(111) surface by using a scanning tunneling microscope and show that they mediate the spin-dependent recombination of the bound holes of the boron acceptor via direct visualization. This recombination is the intraband process and is significantly affected by the spin-orbit coupling effect. We also demonstrate that such a paramagnetic center with a boron acceptor at its neighbor site can be produced with atomic precision, which makes it a promising candidate for implementing position-controlled impurity qubits with an electrical readout mechanism in silicon.