Electrical Properties of Self-Assembled Nano-Schottky Diodes

A bottom-up methodology to fabricate a nanostructured material by Au nanoclusters on 6H-SiC surface is illustrated. Furthermore, a methodology to control its structural properties by thermal-induced self-organization of the Au nanoclusters is demonstrated. To this aim, the self-organization kinetic mechanisms of Au nanoclusters on SiC surface were experimentally studied by scanning electron microscopy, atomic force microscopy, Rutherford backscattering spectrometry and theoretically modelled by a ripening process. The fabricated nanostructured materials were used to probe, by local conductive atomic force microscopy analyses, the electrical properties of nano-Schottky contact Au nanocluster/SiC. Strong efforts were dedicated to correlate the structural and electrical characteristics: the main observation was the Schottky barrier height dependence of the nano-Schottky contact on the cluster size. Such behavior was interpreted considering the physics of few electron quantum dots merged with the concepts of ballistic transport and thermoionic emission finding a satisfying agreement between the theoretical prediction and the experimental data. The fabricated Au nanocluster/SiC nanocontact is suggested as a prototype of nano-Schottky diode integrable in complex nanoelectronic circuits

Apparatus for synthesizing and separating synthesis products e.g. gaseous and liquid phases on bed, maintains heavier liquid phase at lower portion of first meatus due to gravity and lighter liquid phase at upper portion of meatus

NOVELTY - The apparatus has header that is set to make the heavier and lighter liquid phases flow along outer side surface of a third tube (8) as far as first closure element (13). The third tube is provided with second side openings for directly connecting the first and second meatus. The heavier liquid phase is maintained at lower portion of the first meatus due to gravity and lighter liquid phase is maintained at upper portion of the first meatus until the liquid phases fall into a fourth tube (9). The heavier liquid phase is collectible through a collection hole (12). USE - Apparatus e.g. reactor/separator for synthesizing and separating synthesis products e.g. gaseous phase and heavier and lighter liquid phases on catalytic bed, used in production of biodiesel. ADVANTAGE - Since heavier liquid phase is maintained at lower portion of the first meatus due to gravity and lighter liquid phase is maintained at upper portion of the first meatus, sedimentation separation of the liquid phases is improved. The structure of the apparatus is simplified and the apparatus is constructed easily. The efficacy and use of catalyst are maximized. DETAILED DESCRIPTION - The apparatus has synthesis module (M1) that is set with a first tube (1) which is provided with an opening at one end and closed at second end by a mesh (7). The first tube is adapted to contain a catalytic bed (6). A separation module (M2) is set to separate heavier and lighter liquid phases and gaseous phase originating from the synthesis module. A second tube (1') is arranged adjacent to second end of the first tube. A first closure element is provided with a through hole for sole passage of the second liquid and of the gaseous phase. A third tube is affixed to first end of second tube. A first meatus is set between second tube and the third tube. The fourth tube is set inside the third tube so as to define a second meatus between the third tube and the fourth tube. A separation zone is set between the heavier and lighter liquid phases. A collection hole is set in the second tube to collect the heavier liquid phase. The third tube is set with first side openings at first end, and is set with a header for collecting the liquid phases originating from the synthesis module. The first meatus is directly inserted into the third tube and subsequently into the fourth tube. A control system is set between the liquid phases, to check and maintain interface level below the upper end of the first side openings. The control system has interface level indicator that is connected to the second tube by second side holes envisaged in side surface of the second tube. One of the second side holes is arranged in proximity of the first closure element and other is positioned above the upper end of the first side openings. The protrusions are arranged along cylindrical side surface of the third tube, and are separated by spaces for passage of the liquid phases from the header to the first meatus. A redistribution module (M3) is set to redistribute the lighter liquid phase and gaseous phase originating from the fourth tube. A fifth tube (1") is arranged adjacent to second end of the second tube. The closure element is set with a central perforated area. A sixth tube (14) is set to descent and release of the gaseous phase. The central perforated area is provided with several holes for homogeneous distribution of lighter liquid phase downstream of the redistribution module. The sixth tube is affixed to a second closure element (15). The mesh is provided with a passage area. The synthesis module, separation module and redistribution module are vertically-stacked. An INDEPENDENT CLAIM is included for a method for synthesizing and separating synthesis products e.g. gaseous phase and heavier and lighter liquid phases on catalytic bed, involves synthesizing on a catalytic bed and producing the synthesis products. The liquid phases and gaseous phase are separated in the separation module

Nanoscale characterization of electrical transport at metal/3C-SiC interfaces

In this work, the transport properties of metal/3C-SiC interfaces were monitored employing a nanoscale characterization approach in combination with conventional electrical measurements. In particular, using conductive atomic force microscopy allowed demonstrating that the stacking fault is the most pervasive, electrically active extended defect at 3C-SiC(111) surfaces, and it can be electrically passivated by an ultraviolet irradiation treatment. For the Au/3C-SiC Schottky interface, a contact area dependence of the Schottky barrier height (ΦB) was found even after this passivation, indicating that there are still some electrically active defects at the interface. Improved electrical properties were observed in the case of the Pt/3C-SiC system. In this case, annealing at 500°C resulted in a reduction of the leakage current and an increase of the Schottky barrier height (from 0.77 to 1.12 eV). A structural analysis of the reaction zone carried out by transmission electron microscopy [TEM] and X-ray diffraction showed that the improved electrical properties can be attributed to a consumption of the surface layer of SiC due to silicide (Pt2Si) formation. The degradation of Schottky characteristics at higher temperatures (up to 900°C) could be ascribed to the out-diffusion and aggregation of carbon into clusters, observed by TEM analysis