Single-Electron Transistor in Strained Si/SiGe Heterostructures

A split gate technique is used to form a lateral quantum dot in a two-dimensional electron gas of a modulation-doped silicon/silicon-germanium heterostructure. e-beam lithography was employed to produce split gates. By applying negative voltages to these gates the underlying electron gas is depleted and a lateral quantum dot is formed, the size of which can be adjusted by the gate voltage. We observe single-electron operation with Coulomb blockade behavior below 1K. Gate leakage currents are well controlled, indicating that the recently encountered problems with Schottky gates for this type of application are not an inherent limitation of modulation-doped Si/SiGe heterostructures, as had been speculated.Comment: 3 page

CCM.FF-K3.2011 Intercomparison for airspeed

The CCM.FF-K3.2011 comparison was organized for the purpose of determination of the degree of equivalence of the national standards for air speed over the range 0.5 m/s to 40 m/s. An ultrasonic anemometer and a Laser Doppler anemometer were used as transfer standards. Nine laboratories from three RMOs participated between July 2013 and July 2015 – EURAMET: PTB, Germany; LNE-CETIAT, France; INRIM, Italy; VSL, The Netherlands; E+E, Austria; SIM: NIST, measurements were provided at ambient conditions. All results of independent participants were used in the determination of the key comparison reference value (KCRV) and the uncertainty of the KCRV. The reference value was determined at each air speed separately following “procedure A” presented by M. G. Cox. The degree of equivalence with the KCRV was calculated for each air speed and laboratory. Almost all reported results were consistent with the KCRV

Colloidal HgTe Nanocrystals with Widely Tunable Narrow Band Gap Energies: From Telecommunications to Molecular Vibrations

For the visible 1 and the near-IR 2 spectral region, a multitude of highly luminescent wide-gap semiconductor nanocrystals (NCs) have been chemically synthesized. Despite the enormous success of colloidal NCs, used, for example, in lasers, 3 as fluorescent markers 4 in biological systems, or in single photon sources, 5 the development of NCs with tunable IR emission up to wavelengths of more than 3 µm is still challenging. 6 Hg chalcogenides are most appropriate to obtain narrow band gaps from NCs in the quantum confinement regime because their bulk constituents exhibit zero band gaps, whereas those of all alternative binary narrow gap semiconductors, such as lead chalcogenides and group III antimonides, are at least 0.18 eV (InSb, 300 K). 7 So far, the best synthetic routes to Hg chalcogenide NCs are those based on thiol-capping in aqueous medium. 8,9 The optical characterization of NCs in aqueous solutions is, however, restricte