We present the findings of spin-dependent single-hole and pair-hole transport in plane and across the p-type high mobility silicon quantum wells (Si-QW), 2 nm, confined by the superconductor δ-barriers on the n-type ...We present the findings of spin-dependent single-hole and pair-hole transport in plane and across the p-type high mobility silicon quantum wells (Si-QW), 2 nm, confined by the superconductor δ-barriers on the n-type Si (100) surface. The oscillations of the conductance in normal state and the zero-resistance supercurrent in superconductor state as a function of the top gate voltage are found to be correlated by on- and off-resonance tuning the two-dimensional levels of holes in Si-QW with the Fermi energy in the superconductor δ-barriers. The SIMS and STM studies have shown that the δ-barriers heavily doped with boron, 5 × 1021 cm–3, represent really alternating arrays of silicon empty and doped dots, with dimensions restricted to 2 nm. This concentration of boron seems to indicate that each doped dot located between empty dots contains two impurity atoms of boron. The EPR studies show that these boron pairs are the trigonal dipole centres, B+ - B–, that contain the pairs of holes, which result from the negative -U reconstruction of the shallow boron acceptors, 2B0 => B+ - B–. The electrical resistivity, magnetic susceptibility and specific heat measurements demonstrate that the high density of holes in the Si-QW (> 1011 cm–2) gives rise to the high temperature superconductor properties for the δ-barriers. 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 quantization of the supercurrent and the multiple Andreev reflection (MAR) observed both across and along the Si-QW plane thereby identifying the spin transistor effect.展开更多
We present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the ultra-shallow p-type silicon quantum well (Si-QW), 2 nm, confined by the δ-barriers heavily doped with...We present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the ultra-shallow p-type silicon quantum well (Si-QW), 2 nm, confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. This longitudinal quantum conductance staircase, Gxx, is revealed by the voltage applied to the Hall contacts, Vxy, to a maximum of 4e2/h. In addition to the standard plateau, 2e2/h, the variations of the Vxy voltage appear to exhibit the fractional forms of the quantum conductance staircase with the plateaus and steps that bring into correlation respectively with the odd and even fractional values.展开更多
文摘We present the findings of spin-dependent single-hole and pair-hole transport in plane and across the p-type high mobility silicon quantum wells (Si-QW), 2 nm, confined by the superconductor δ-barriers on the n-type Si (100) surface. The oscillations of the conductance in normal state and the zero-resistance supercurrent in superconductor state as a function of the top gate voltage are found to be correlated by on- and off-resonance tuning the two-dimensional levels of holes in Si-QW with the Fermi energy in the superconductor δ-barriers. The SIMS and STM studies have shown that the δ-barriers heavily doped with boron, 5 × 1021 cm–3, represent really alternating arrays of silicon empty and doped dots, with dimensions restricted to 2 nm. This concentration of boron seems to indicate that each doped dot located between empty dots contains two impurity atoms of boron. The EPR studies show that these boron pairs are the trigonal dipole centres, B+ - B–, that contain the pairs of holes, which result from the negative -U reconstruction of the shallow boron acceptors, 2B0 => B+ - B–. The electrical resistivity, magnetic susceptibility and specific heat measurements demonstrate that the high density of holes in the Si-QW (> 1011 cm–2) gives rise to the high temperature superconductor properties for the δ-barriers. 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 quantization of the supercurrent and the multiple Andreev reflection (MAR) observed both across and along the Si-QW plane thereby identifying the spin transistor effect.
文摘We present the findings for the quantum conductance staircase of holes that is caused by the edge channels in the ultra-shallow p-type silicon quantum well (Si-QW), 2 nm, confined by the δ-barriers heavily doped with boron on the n-type Si (100) surface. This longitudinal quantum conductance staircase, Gxx, is revealed by the voltage applied to the Hall contacts, Vxy, to a maximum of 4e2/h. In addition to the standard plateau, 2e2/h, the variations of the Vxy voltage appear to exhibit the fractional forms of the quantum conductance staircase with the plateaus and steps that bring into correlation respectively with the odd and even fractional values.
