Superconductivity in silicon nanostructures
We present the findings of single-hole and pair-hole tunneling into the negative-U centres at the quantum well—δ-barrier interfaces that seems to give rise to the superconductivity observed in the silicon nanostructures prepared by short time diffusion of boron on the n-type Si(100) surface. These S...
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Veröffentlicht in: | Physica. C, Superconductivity Superconductivity, 2006-05, Vol.437-438, p.21-24 |
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Sprache: | eng |
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Zusammenfassung: | We present the findings of single-hole and pair-hole tunneling into the negative-U centres at the quantum well—δ-barrier interfaces that seems to give rise to the superconductivity observed in the silicon nanostructures prepared by short time diffusion of boron on the n-type Si(100) surface. These Si-based nanostructures represent the p-type ultra-narrow self-assembled silicon quantum wells, 2nm, confined by the δ-barriers heavily doped with boron, 3nm. The EPR and the thermo-emf studies show that the δ-barriers appear to consist of the trigonal dipole centres, B+–B−, which are caused by the negative-U reconstruction of the shallow boron acceptors, 2B0→B++B−. Using the CV and thermo-emf techniques, the transport of two-dimensional holes inside SQW is demonstrated to be accompanied by single-hole tunneling through these negative-U centres that results in the superconductivity of the δ-barriers, which seems to be in frameworks of the mechanism suggested by E. Simanek and C.S. Ting (Sol. St. Commun. 32 (1979) 731; Phys. Rev. Lett. 45 (1980) 1213). The values of the correlation gaps obtained from these measurements are in a good agreement with the data derived from the temperature and magnetic field dependencies of the magnetic susceptibility, which reveal a strong diamagnetism and additionally identify the superconductor gap value. |
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ISSN: | 0921-4534 1873-2143 |
DOI: | 10.1016/j.physc.2005.12.011 |