Abstract. We present the findings of the superconductivity in the silicon nanostructures prepared by short time diffusion of boron after preliminary oxidation of the n-type Si (100) surface. These Si-based nanostructures represent the ptype high mobility silicon quantum well (Si-QW) confined by the δ -barriers heavily doped with boron. The ESR studies show that the δ -barriers appear to consist of the trigonal dipole centers, B + -B -, which are caused by the negative-U reconstruction of the shallow boron acceptors, 2B 0 → B + + B -. The temperature and magnetic field dependencies of the resistance, thermo-emf, specific heat and magnetic susceptibility demonstrate that the high temperature superconductivity observed seems to result from the transfer of the small hole bipolarons through these negative-U dipole centers of boron at the Si-QW -δ-barrier interfaces. The value of the superconductor energy gap obtained is in a good agreement with the data derived from the oscillations of the conductance in normal state and of the zero-resistance supercurrent in superconductor state as a function of the bias voltage. These oscillations appear to be correlated by on-and off-resonance tuning the two-dimensional subbands of holes with the Fermi energy in the superconductor δ-barriers. Finally, the proximity effect in the S-Si-QW-S structure is revealed by the findings of the multiple Andreev reflection (MAR) processes and the quantization of the supercurrent.

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We present the first findings of the silicon vacancy related centers identified in the non irradiated 6H SiC nanostructure using the electron spin resonance (ESR) and electrically detected (ED) ESR tech nique. This planar 6H SiC nanostructure represents the ultra narrow p type quantum well confined by the δ barriers heavily doped with boron on the surface of the n type 6H SiC (0001) wafer. The new EDESR tech nique by measuring the only magnetoresistance of the 6H SiC nanostructure under the high frequency gen eration from the δ barriers appears to allow the identification of the isolated silicon vacancy centers as well as the triplet center with spin state S = 1. The same triplet center that is characterized by the large value of the zero field splitting constant D and anisotropic g factor is revealed by the ESR (X band) method. The hyper fine (HF) lines in the ESR and EDESR spectra originating from the HF interaction with the 14 N nucleus seem to attribute this triplet center to the N-V Si defect.