A first-principles study of the electronic structure of deterministically implanted donor arrays in silicon: multi-valley effects

Deterministically implanted donors in silicon provide an important route to develop quantum gates, analogue quantum simulators, and other atomic-scale devices [1]. We have computed the optical properties of a series of donor lines with up to 10 atoms in the sphereical-band approximation (single isotropic valley) [2]. Our calculations show charge-transfer excitations play an important role, dominating the transition for separation ~5nm and dropping down to 10 meV. We have also performed multi-valley calculations (with conduction-band anisotropy) for a donor pair and a three-donor linear cluster, which show distinct features in the excitation spectra arising from valley interaction. One consequence is to open up a gap between the ionic-state and the 1s→2p intra-atom transition [3]. Single-valley calculations can be useful to understand the excited states of valley-polarized electrons [4]. Our calculations thus provide solid theoretical foundation to many promising applications for donor arrays, including valleytronics, quantum terahertz cascade laser devices, and quantum information technology.

[1] J. Salfi, et. al., Nat. Commun. 7, 11342 (2016).
[2] Wei Wu, et. al., Phys. Rev. B, 97, 035205 (2018).
[3] Wei Wu, et. al., In preparation.
[4] J. Salfi, et. al., Nat. Mat., 13, 605 (2014).