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Spectroscopy of few-electron single-crystal silicon quantum dots


A defining feature of modern CMOS devices1 and almost all quantum semiconductor devices2,3,4,5,6,7,8,9 is the use of many different materials. For example, although electrical conduction often occurs in single-crystal semiconductors, gates are frequently made of metals and dielectrics are commonly amorphous. Such devices have demonstrated remarkable improvements in performance over recent decades, but the heterogeneous nature of these devices can lead to defects at the interfaces between the different materials, which is a disadvantage for applications in spintronics10,11 and quantum information processing12,13,14,15,16. Here we report the fabrication of a few-electron quantum dot in single-crystal silicon that does not contain any heterogeneous interfaces. The quantum dot is defined by atomically abrupt changes in the density of phosphorus dopant atoms, and the resulting confinement produces novel effects associated with energy splitting between the conduction band valleys. These single-crystal devices offer the opportunity to study how very sharp, atomic-scale confinement—which will become increasingly important for both classical and quantum devices—influences the operation and performance of devices.

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Figure 1: Few-electron single-crystal silicon quantum dot device.
Figure 2: Stability diagram of the few-electron single-crystal silicon quantum dot.
Figure 3: Excited-state spectrum of a few-electron single-crystal silicon quantum dot.
Figure 4: Contribution of the tunnelling density of states from the irregularly shaped leads.

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The authors gratefully acknowledge discussions with G. Klimeck and L.C.L. Hollenberg. This work was supported by the Australian Research Council, the Army Research Office (ARO) under contract no. W911NF-08-1-0527. M.Y.S. acknowledges a Federation Fellowship. The work at Wisconsin was supported by ARO under award W911NF-08-1-0482 and by the National Science Foundation under grant no. DMR-0805045.

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M.Fu. carried out the fabrication and measurements. M.Fr. conducted the theoretical work. M.Fu., S.M., F.Z., M.S. and M.E. analysed the data. M.S. planned the project. M.Fu., M.S., M.Fr. and M.E. prepared the manuscript.

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Correspondence to Michelle Y. Simmons.

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The authors declare no competing financial interests.

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Fuechsle, M., Mahapatra, S., Zwanenburg, F. et al. Spectroscopy of few-electron single-crystal silicon quantum dots. Nature Nanotech 5, 502–505 (2010).

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