Orbital Stark effect and quantum confinement transition of donors in silicon

Rajib Rahman, G. P. Lansbergen, Seung H. Park, J. Verduijn, Gerhard Klimeck, S. Rogge, and Lloyd C. L. Hollenberg
Phys. Rev. B 80, 165314 – Published 9 October 2009

Abstract

Adiabatic shuttling of single impurity bound electrons to gate-induced surface states in semiconductors has attracted much attention in recent times, mostly in the context of solid-state quantum computer architecture. A recent transport spectroscopy experiment for the first time was able to probe the Stark shifted spectrum of a single donor in silicon buried close to a gate. Here, we present the full theoretical model involving large-scale quantum mechanical simulations that was used to compute the Stark shifted donor states in order to interpret the experimental data. Use of atomistic tight-binding technique on a domain of over a million atoms helped not only to incorporate the full band structure of the host, but also to treat realistic device geometries and donor models, and to use a large enough basis set to capture any number of donor states. The method yields a quantitative description of the symmetry transition that the donor electron undergoes from a three-dimensional Coulomb confined state to a two-dimensional (2D) surface state as the electric field is ramped up adiabatically. In the intermediate field regime, the electron resides in a superposition between the atomic donor states and the 2D surface states. In addition to determining the effect of field and donor depth on the electronic structure, the model also provides a basis to distinguish between a phosphorus and an arsenic donor based on their Stark signature. The method also captures valley-orbit splitting in both the donor well and the interface well, a quantity critical to silicon qubits. The work concludes with a detailed analysis of the effects of screening on the donor spectrum.

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  • Received 28 April 2009

DOI:https://doi.org/10.1103/PhysRevB.80.165314

©2009 American Physical Society

Authors & Affiliations

Rajib Rahman1,*, G. P. Lansbergen2, Seung H. Park1, J. Verduijn2, Gerhard Klimeck1,3, S. Rogge2, and Lloyd C. L. Hollenberg4,†

  • 1Network for Computational Nanotechnology, Purdue University, West Lafayette, Indiana 47907, USA
  • 2Kavli Institute of Nanoscience, Delft University of Technology, Delft, Lorentzweg 1, 2628 CJ Delft, The Netherlands
  • 3Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California 91109, USA
  • 4Center for Quantum Computer Technology, School of Physics, University of Melbourne, Victoria 3010, Australia

  • *rrahman@purdue.edu
  • lloydch@unimelb.edu.au

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Issue

Vol. 80, Iss. 16 — 15 October 2009

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