Abstract. We report electronic transport on n-type silicon Single Electron Transistors (SETs) fabricated in Complementary Metal Oxide Semiconductor (CMOS) technology. The n-MOSSETs are built within a pre-industrial Fully Depleted Silicon On Insulator (FDSOI) technology with a silicon thickness down to 10 nm on 200 mm wafers. The nominal channel size of 20×20 nm 2 is obtained by employing electron beam lithography for active and gate levels patterning. The Coulomb blockade stability diagram is precisely resolved at 4.2 K and it exhibits large addition energies of tens of meV. The confinement of the electrons in the quantum dot has been modeled by using a Current Spin Density Functional Theory (CS-DFT) method. CMOS technology enables massive production of SETs for ultimate nanoelectronics and quantum variables based devices.
We present a novel method, based on vortex imaging by low-temperature scanning electron microscopy (LTSEM), to directly image the sheet-current distribution in YBa2Cu3O7 dc SQUID washers. We show that the LTSEM vortex signals are simply related to the scalar stream function describing the vortex-free circulating sheet-current distribution J . Unlike previous inversion methods that infer the current distribution from the measured magnetic field, our method uses pinned vortices as local detectors for J . Our experimental results are in very good agreement with numerical calculations of J .PACS numbers: 68.37. Hk, 74.25.Op, 85.25.Dq Spatially resolved techniques can provide important insight into current flow, arrangement of vortices, flux pinning, and noise in superconductors and their mutual interactions. So far there has been only one method of imaging the current distribution in superconductors: The magnetic field distribution on top of a superconducting thin film is measured, e.g. by magneto-optics, from which the current distribution can then be calculated by inverting the Biot-Savart law [1].In this paper we present a novel method to directly image the sheet-current distribution in a YBa 2 Cu 3 O 7 thin film. We use low-temperature scanning electron microscopy (LTSEM) [2,3,4,5] to image vortices in dc SQUID washers [6,7]. Most techniques for vortex imaging, such as Lorentz microscopy [8], scanning SQUID microscopy [9,10], scanning Hall microscopy [11] or magneto-optics[12] rely on the detection of the stray magnetic field produced in close proximity to a vortex. In contrast, vortex imaging by LTSEM is different from those techniques, as it is based on the electron-beaminduced apparent displacement of a vortex, pinned at position r in the (x, y)-plane of a SQUID washer, which is detected as a change of stray magnetic flux Φ(r) coupled to the SQUID. Hence, the contrast of the LTSEM vortex signals directly senses ∇Φ(r). Recently, Clem and Brandt [13] have shown that Φ(r) is proportional to the scalar stream function G(r) that describes the circulating sheet-current density J(r) flowing in the vortex-free case at position r in the SQUID washer. In this paper we show that this relationship allows us to use the vortices as local detectors for J(r): At each position a vortex has been imaged, we can directly determine J(r) without complicated calculations.In our experiments, we investigated several dc SQUID washers [see Fig. 1(a)] fabricated from epitaxially grown d=80 nm thick c-axis oriented YBa 2 Cu 3 O 7 (YBCO) thin * Electronic address: koelle@uni-tuebingen.de films. We will present an analysis of LTSEM data obtained from one representative device with washer size 120 µm × 305 µm, with a 100 µm long and 4 µm wide slit. The 1 µm wide Josephson junctions are formed by a 24 • symmetric grain boundary in the underlying SrTiO 3 substrate. For imaging by LTSEM, the YBCO SQUIDs are mounted on a magnetically shielded, liquid nitrogen cooled cryostage of an SEM [14] and read out by a standard flux-locked loop (FLL) w...
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