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# Spatial metrology of dopants in silicon with exact lattice site precision

## Abstract

Scaling of Si-based nanoelectronics has reached the regime where device function is affected not only by the presence of individual dopants, but also by their positions in the crystal. Determination of the precise dopant location is an unsolved problem in applications from channel doping in ultrascaled transistors to quantum information processing. Here, we establish a metrology combining low-temperature scanning tunnelling microscopy (STM) imaging and a comprehensive quantum treatment of the dopant–STM system to pinpoint the exact coordinates of the dopant in the Si crystal. The technique is underpinned by the observation that STM images contain atomic-sized features in ordered patterns that are highly sensitive to the STM tip orbital and the absolute dopant lattice site. The demonstrated ability to determine the locations of P and As dopants to 5 nm depths will provide critical information for the design and optimization of nanoscale devices for classical and quantum computing applications.

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## Acknowledgements

This work is funded by the Australian Research Council Center of Excellence for Quantum Computation and Communication Technology (CE110001027) and in part by the US Army Research Office (W911NF-08-1-0527). M.Y.S. acknowledges an ARC Laureate Fellowship. This work is supported by the European Commission Future and Emerging Technologies Proactive Project MULTI (317707). Computational resources are acknowledged from NCN/Nanohub. M.U. thanks C. Hill and V. Perunicic for discussions.

## Author information

Authors

### Contributions

L.C.L.H. and M.U. formulated the theoretical framework for the metrology scheme, including tight-binding calculations of the STM images with generic tip orbitals with input from J.S. M.U. performed the theoretical calculations. J.B., J.S., B.V., M.Y.S. and S.R. designed and conducted the STM measurements. L.C.L.H. and M.U. wrote the manuscript with input from all authors.

### Corresponding authors

Correspondence to M. Usman or L. C. L. Hollenberg.

## Ethics declarations

### Competing interests

The authors declare no competing financial interests.

## Supplementary information

### Supplementary information

Supplementary information (PDF 2556 kb)

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Usman, M., Bocquel, J., Salfi, J. et al. Spatial metrology of dopants in silicon with exact lattice site precision. Nature Nanotech 11, 763–768 (2016). https://doi.org/10.1038/nnano.2016.83

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• DOI: https://doi.org/10.1038/nnano.2016.83

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