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Single-donor ionization energies in a nanoscale CMOS channel

Abstract

One consequence of the continued downward scaling of transistors is the reliance on only a few discrete atoms to dope the channel, and random fluctuations in the number of these dopants are already a major issue in the microelectronics industry1. Although single dopant signatures have been observed at low temperatures2,3,4,5,6,7,8, the impact on transistor performance of a single dopant atom at room temperature is not well understood. Here, we show that a single arsenic dopant atom dramatically affects the off-state room-temperature behaviour of a short-channel field-effect transistor fabricated with standard microelectronics processes. The ionization energy of the dopant is measured to be much larger than it is in bulk, due to its proximity to the buried oxide9,10, and this explains the large current below threshold and large variability in ultra-scaled transistors. The results also suggest a path to incorporating quantum functionalities into silicon CMOS devices through manipulation of single donor orbitals.

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Figure 1: Geometry, simulations and electrical characteristics of the devices.
Figure 2: Differential source–drain conductance versus gate and drain voltages at 4.2 K for the sample with the largest off-state current (blue line in Fig. 1d).
Figure 3: Coulomb blockade spectroscopy of the first dopant atom.
Figure 4: Magnetic field dependence of the first peak.
Figure 5: The second and third peaks of Fig. 2b recorded at T = 100 mK, respectively corresponding to the D+ → D0 transition (second) and D0 → D transition (third).

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Acknowledgements

The authors thank I. Martin Bragado and D. Conrad from SYNOPSYS for helpful discussions about KMC simulations using SPROCESS. The authors are grateful to C. Delerue for valuable discussions.

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Contributions

R.W. and M.V. fabricated the devices and O.C. performed the doping simulations. M.P., X.J. and M.S. designed and performed the low-temperature experiment. All the authors analysed the data and co-wrote the paper.

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Correspondence to M. Sanquer.

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The authors declare no competing financial interests.

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Pierre, M., Wacquez, R., Jehl, X. et al. Single-donor ionization energies in a nanoscale CMOS channel. Nature Nanotech 5, 133–137 (2010). https://doi.org/10.1038/nnano.2009.373

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