Exact location of dopants below the Si(001):H surface from scanning tunnelling microscopy and density functional theory

Abstract

Control of dopants in silicon remains the most important approach to tailoring the properties of electronic materials for integrated circuits, with Group V impurities the most important n-type dopants. At the same time, silicon is finding new applications in coherent quantum devices, thanks to the magnetically quiet environment it provides for the impurity orbitals. The ionization energies and the shape of the dopant orbitals depend on the surfaces and interfaces with which they interact. The location of the dopant and local environment effects will therefore determine the functionality of both future quantum information processors and next-generation semiconductor devices. Here we match observed dopant wavefunctions from low-temperature scanning tunnelling microscopy (STM) to images simulated from first-principles density functional theory (DFT) calculations. By this combination of experiment and theory we precisely determine the substitutional sites of neutral As dopants between 5 and 15A below the Si(001):H surface. In the process we gain a full understanding of the interaction of the donor-electron state with the surface, and hence of the transition between the bulk dopant (with its delocalised hydrogenic orbital) and the previously studied dopants in the surface layer.

12 pages; accepted for publication in Phys. Rev. B

References in corpus (7)

• Spatial structure of an individual Mn acceptor in GaAs
• Coherent Control of Rydberg States in Silicon
• Quantum Simulation of the Hubbard Model with Dopant Atoms in Silicon
• Spatial Metrology of Dopants in Silicon with Exact Lattice Site Precision
• STM images of sub-surface Mn atoms in GaAs: evidence of hybridization of surface and impurity states
• Spatially resolved resonant tunneling on single atoms in silicon
• Donor Wavefunctions in Si Gauged by STM Images

Cited by in corpus (6)

• Valley interference and spin exchange at the atomic scale in silicon
• Atomic-level Characterisation of Quantum Computer Arrays by Machine Learning
• Towards visualisation of central-cell-effects in scanning-tunnelling-microscope images of subsurface dopant qubits in silicon
• Non-destructive X-ray imaging of patterned delta-layer devices in silicon
• Novel characterisation of dopant-based qubits
• Excited states of defect lines in silicon: A first-principles study based on hydrogen cluster analogues