The processing parameters which favour the onset of an impurity band conduction around room temperature with a contemporaneous elevated p-type conductivity in Al+ implanted 4H-SiC are highlighted by comparing original and literature results. In the examined cases, Al is implanted at 300–400 °C, in concentrations from below to above the Al solubility limit in 4H-SiC (2 × 1020 cm−3) and post implantation annealing temperature is ≥1950 °C. Transport measurements feature the onset of an impurity band conduction, appearing at increasing temperature for increasing Al implant dose, until this transport mechanism is enabled around room temperature. This condition appears suitable to guarantee a thermal stability of the electrical properties. In this study, the heaviest doped and less resistive samples (Al implanted concentration of 5 × 1020 cm−3 and resistivity of about 2 × 10−2 Ω cm) show a carrier density above the Al solubility limit, which is consistent with at least a 50% electrical activation for a 15% compensation. The model of Miller and Abrahams well describes the resistivity data of the lower doped sample, whereas a deviation from the behaviour predicted by such a model is observed in the higher doped specimens, consistent with the occurrence of a variable range hopping at low temperature.

We report the first experimental demonstration of an electrostatic electron orbital angular momentum (OAM) sorter, which can be used to analyze the OAM states of electrons in a transmission electron microscope. We verify the sorter functionality for several electron beams possessing different superpositions of OAM states, and use it to record the electron beams OAM spectra. Our current electrostatic OAM sorter has an OAM resolution of 2 in the units of ℏ -the reduced Planck constant. It is expected to increase the OAM resolution of the sorter to the optimal resolution of 1 in the future via fine control of the sorting phase elements.

Micro and nanotechnologies are called to play a key role in the fabrication of small and low cost sensors with excellent performance enabling new continuous monitoring scenarios and distributed intelligence paradigms (Internet of Things, Trillion Sensors). Harvesting devices providing energy autonomy to those large numbers of microsensors will be essential. In those scenarios where waste heat sources are present, thermoelectricity will be the obvious choice. However, miniaturization of state of the art thermoelectric modules is not easy with the current technologies used for their fabrication. Micro and nanotechnologies offer an interesting alternative considering that silicon in nanowire form is a material with a promising thermoelectric figure of merit. This paper presents two approaches for the integration of large numbers of silicon nanowires in a cost-effective and practical way using only micromachining and thin-film processes compatible with silicon technologies. Both approaches lead to automated physical and electrical integration of medium-high density stacked arrays of crystalline or polycrystalline silicon nanowires with arbitrary length (tens to hundreds microns) and diameters below 100 nm.

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A new Micro-Opto-Mechanical System (MOMS) technology for the fabrication of optoacoustic probes on optical fiber is presented. The technology is based on the thermoelastic emission of ultrasonic waves from patterned carbon films for generation and on extrinsic polymer Fabry-Perot acousto-optical transducers for detection, both fabricated on miniaturized single-crystal silicon frames used to mount the ultrasonic transducers on the tip of an optical fiber. Thanks to the fabrication process adopted, high miniaturization levels are reached in the MOMS devices, demonstrating fiber-optic emitters and detectors with minimum diameter around 350 and 250 μm respectively. A thorough functional testing of the ultrasound emitters mounted on 200 and 600 μm diameter optical fibers is presented, in which the fiber-optic emitter with a diameter of 200 μm shows generated acoustic pressures with peak-to-peak value up to 2.8 MPa with rather flat emission spectra extended beyond 150 MHz. The possibility to use the presented optoacoustic sources in conjunction with the fiber-optic acousto-optical detectors within a minimally invasive probe is also demonstrated by successfully measuring the ultrasonic echo reflected from a rigid surface immersed in water with various concentration of scatterers. The resulting spectra highlight the possibility to discriminate the effects due to frequency selective attenuation in a very wide range of frequencies within a biological medium using the presented fiber-optic probes.