We present the fabrication of vertically aligned cobalt nanowire arrays on planar surfaces as well as preliminary field-emission (FE) experiments using them as cold electron cathodes. These arrays are obtained by electrodeposition into nanoporous templates on Au/Ti/Si substrates at very low temperature (<100 °C). After the removal of the template, the arrays consist of statistically positioned vertical free-standing nanowires with high aspect ratios, uniform dimensions, and predetermined densities. The electron field-emission measurements show metallic and reproducible characteristics. Emission is found to be reasonably homogeneous over the whole sample area, and a current density of 1 mA/cm2 has been obtained. We show that the growth process permits us to predetermine the field amplification factor precisely, which is of primary importance for FE sources. A large variety of FE applications can be envisaged, including FE displays and microwave amplifiers.

In order to assess possible mechanisms of gate reverse-bias leakage current in AlInN/GaN high electron mobility transistors (HEMTs) grown by metalorganic chemical-vapor deposition on SiC substrates, temperature-dependent current-voltage measurements combined with Fourier transform current deep level transient spectroscopy (FT-CDLTS) are performed in the temperature range of 200–400 K. In this range of temperature reverse-bias leakage current flow is found to be dominated by Poole–Frenkel emission. Based on CDLTS measurements, a model of leakage current transport via a trap state located at the AlInN/metal interface with an activation energy of 0.37 eV is suggested. The trap nature is shown to be an extended trap, most probably associated with dislocations in the AlInN barrier layer.

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A study of the electrical performances of AlInN/GaN High Electron Mobility Transistors (HEMTs) on SiC substrates is presented in this paper. Four different wafers with different technological and epitaxial processes were characterized. Thanks to intensive characterizations as pulsed-IV, [S]-parameters, and load-pull measurements from S to Ku bands, it is demonstrated here that AlInN/GaN HEMTs show excellent power performances and constitute a particularly interesting alternative to AlGaN/GaN HEMTs, especially for high-frequency applications beyond the X band. The measured transistors with 250 nm gate lengths from different wafers delivered in continuous wave (cw): 10.8 W/mm with 60% associated power added efficiency (PAE) at 3,5 GHz, 6.6 W/mm with 39% associated PAE at 10.24 GHz, and 4.2 W/mm with 43% associated PAE at 18 GHz.

We investigate some properties of an atom chip made of a gold microcircuit deposited on a transparent silicon carbide substrate. A favorable thermal behavior is observed in the presence of electrical current, twice as good as a silicon counterpart. We obtain one hundred million rubidium atoms in a magneto-optical trap with several of the beams passing through the chip. We point out the importance of coating of the chip against reflection to avoid a temperature-dependent Fabry-Perot effect. We finally discuss detection through the chip, potentially granting large numerical apertures, as well as some other potential applications.

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