Electrical Transport and Fluctuation Processes in NbRe and NbReN Ultrathin Films for Superconducting Electronics Applications

NbRe-based superconducting thin films recently received relevant interest in the field of low-temperature electronics. However, for these materials the electrical conduction mechanisms, in particular in the normal state, still need to be investigated in more detail. Here, NbRe and NbReN films of different thicknesses have been deposited on two different substrates, namely monocrystalline Si and SiO2 buffered Si. The films were characterized by DC electrical transport measurements. Moreover, a connection with the charge carriers fluctuation processes has been made by analyzing the electrical noise generated in the normal state region. Despite the films morphology seems not to be affected by the substrate used, a lower noise level has been found for the ones grown on SiO2, in particular for NbReN. From this study it emerges that both NbRe and NbReN ultrathin films are of very good quality, as far as the low-temperature electrical noise and conduction are concerned, with noise levels competitive with NbN. These results may further support the proposal of using these materials in a nanowire form in the field of superconducting electronics.

Fabrication of Ge30Te 70-xSbx Glasses Alloys and Studying the Effect of Partial Substitution on D.C Electrical Energy Parameters

The non-linear components has been emphasized for its multiple applications in rewritable recording and data storage devices. Chalcogenide glasses materials are promising due to their high refractive index. In this paper, alloys for Ge30Te 70-xSbx glasses semiconductor (where x =0.0, 5, 10, 15 and 20) will be fabricated by melt quenching method. The effect of partial substitution on DC electric power parameters, and its knowledge of electrical conduction mechanisms, were investigated to determine the effect of Antimony on the density of extended states, local states, and in Fermi energy states. The electrical measurements revealed the existence of three conduction mechanisms depend on the temperature: at high temperature the conduction will be in the extended state. The local states are responsible at medium temperature, and at low temperature it will related to the Fermi level. The effect of partial substitution had produced change in all electrical conductivity parameters including the (extended, localized, and Fermi) density of states, the activation energy, tail width (ΔE), hoping transition distance (R), and interatomic distances a.

Electrical conductivity and temperature sensitivity of Cu/Mo co-modified YFeoO ceramics

To develop a new kind of thermistor with the negative temperature coefficient (NTC) behaviour, the Cu/Mo co-doped YFeO3 based ceramics were prepared by wet-chemical synthesis and sintering at 1300?C. The orthorhombic perovskite structure was identified in all ceramics by XRD analysis. The possible valence states of Fe, Cu and Mo in the doped YFeO3 compounds were examined by X-ray photoelectron spectroscopy. By adjusting the concentration of Cu- and Mo-ions, the room temperature resistivity (?25) and temperature-sensitive constant (B25/85) can be modified from 1.13?103 to 3.09?105 ??cm and 3000 to 7000K, respectively. The complex impedances at various temperatures (from 25 to 150?C) are tested and analysed. The results show that both grain and grain boundary exhibit the NTC characteristics. The electrical conduction mechanisms composing of polaron hopping conduction and band conduction were proposed in the YFeO3 based ceramics.

Investigation of the electrical conduction mechanisms in P-type amorphous germanium electrical contacts for germanium detectors in searching for rare-event physics

For the first time, electrical conduction mechanisms in the disordered material system is experimentally studied for p-type amorphous germanium (a-Ge) used for high-purity Ge detector contacts. The localization length and the hopping parameters in a-Ge are determined using the surface leakage current measured from three high-purity planar Ge detectors. The temperature dependent hopping distance and hopping energy are obtained for a-Ge fabricated as the electrical contact materials for high-purity Ge planar detectors. As a result, we find that the hopping energy in a-Ge increases as temperature increases while the hopping distance in a-Ge decreases as temperature increases. The localization length of a-Ge is on the order of $$2.13^{-0.05}_{+0.07}\mathrm{{A}}^\circ $$ 2 . 13 + 0.07 - 0.05 A ∘ to $$5.07^{-0.83}_{+2.58}\mathrm{{A}}^\circ $$ 5 . 07 + 2.58 - 0.83 A ∘ , depending on the density of states near the Fermi energy level within bandgap. Using these parameters, we predict that the surface leakage current from a Ge detector with a-Ge contacts can be much smaller than one yocto amp (yA) at helium temperature, suitable for rare-event physics searches.