Valley population of donor states in highly strained silicon
Abstract
Strain is extensively used to controllably tailor the electronic properties of materials. In the context of indirect band-gap semiconductors such as silicon, strain lifts the valley degeneracy of the six conduction band minima, and by extension the valley states of electrons bound to phosphorus donors. Here, single phosphorus atoms are embedded in an engineered thin layer of silicon strained to 0.8% and their wave function imaged using spatially resolved spectroscopy. A prevalence of the out-of-plane valleys is confirmed from the real-space images, and a combination of theoretical modelling tools is used to assess how this valley repopulation effect can yield isotropic exchange and tunnel interactions in the xy-plane relevant for atomically precise donor qubit devices. Finally, the residual presence of in-plane valleys is evidenced by a Fourier analysis of both experimental and theoretical images, and atomistic calculations highlight the importance of higher orbital excited states to obtain a precise relationship between valley population and strain. Controlling the valley degree of freedom in engineered strained epilayers provides a new competitive asset for the development of donor-based quantum technologies in silicon.
Document Details
- Document Type
- Pub Defense Publication
- Publication Date
- Apr 06, 2022
- Source ID
- 10.1088/2633-4356/ac5d1d
Entities
People
- A. Tankasala
- B Voisin
- B. Bertrand
- Brett C Johnson
- Jeffrey McCallum
- Joel Wong
- Joseph Salfi
- K S H Ng
- Lloyd Hollenberg
- Louis Hutin
- M. Vinet
- Michelle Simmons
- Muhammad Usman
- Nagarajan Valanoor
- Rajib Rahman
- Sven Rogge
Organizations
- Ames Research Center
- United States Army