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Ohmic graphite-metal contacts on oxygen-terminated lightly boron-doped CVD monocrystalline diamond
摘要： A process to obtain ohmic contacts on oxygen-terminated lightly boron-doped CVD monocrystalline diamond films was developed. Samples were contacted by Ti/Au metallic pads in the transmission line model (TLM) configuration. The electric contacts were placed onto a mesa structure produced on the CVD boron-doped layer. One of the samples was additionally implanted with helium ions at 10 keV in order to induce the formation of a graphitic layer underneath the diamond surface before contacting so as to improve electrical conduction. The electrical performance of both devices was characterized by the TLM method and compared. As a result, the sample with metallic electrodes exhibited a small and non-linear electrical conduction, while the graphitic/metallic contacts showed an ohmic behaviour with an estimated specific contact resistance as low as 3.3 × 10-4 Ω.cm2 for a doping level of a few 1017 cm-3. This approach opens the way to more efficient ohmic contacts on intrinsic or low-doped diamond that are crucial for the development of electronic devices and detectors.
关键词： oxygen terminations,graphitization,Ohmic graphite-metal contacts,lightly boron-doped CVD diamond film,ion implantation
更新于2025-09-04 15:30:14
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Propriedades de filmes finos de ZnO:Al depositados sobre substratos de poliimida à temperatura ambiente para aplica??es em dispositivos optoeletr?nicos flexíveis
摘要： This work investigated the properties of ZnO:Al thin films produced by radio frequency magnetron sputtering onto polyimide substrates for use as flexible electrodes in optoelectronic devices. For comparison purposes, films were also grown on soda lime glass. The films were deposited with different working powers, onto substrates kept at room temperature. The effects of the power and thickness on the optical, electrical and structural properties of the films were investigated. Atomic force microscopy images revealed that the films were nanocrystalline, with low surface roughness. Values of sheet resistance and transmittance in the visible range were 8 ?/sq (corresponding to 6x10-4 W.cm) and 75%, respectively, which can be considered satisfactory, particularly taking into consideration that deposition was carried out at room temperature.
关键词： transparent electrical contacts,ZnO:Al,flexible transparent electrodes
更新于2025-09-04 15:30:14
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Effect of surface treatment of printed Ag Schottky contacts on n-GaN epitaxial layers using Ag nanoink: Two dimensional characterization by scanning internal photoemission microscopy
摘要： We report the basic electrical characteristics of Ag Schottky contacts printed on n-GaN epitaxial wafers using Ag nanoink with surface treatment using HCl or an organic solvent. The Ag Schottky contacts treated with HCl showed better current–voltage characteristics and a larger Schottky barrier height than those treated with the organic solvent. Scanning internal photoemission microscopy revealed that the HCl-treated samples exhibited a higher uniformity owing to their higher wettability to the Ag nanoink and electrodes than the organic-solvent-treated samples. These results indicate that the removal of surface oxide layers using HCl is effective even though the GaN surface is printed and annealed in air.
关键词： Ag Schottky contacts,n-GaN,surface treatment,Ag nanoink,scanning internal photoemission microscopy
更新于2025-09-04 15:30:14
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Effect of interfacial voltage on tribological characteristics of polysilicon micro-contacts tested in ambient air under dynamic impact conditions
摘要： A polycrystalline silicon microtribometer was used to examine the evolution of tribological properties under dynamic mechanical impact and hot switching conditions. Changes in surface properties were tracked via periodic static adhesion tests. Surfaces experienced two distinct periods in the course of the dynamic lifetime – a run-in phase with little measurable surface modification and a degradation phase with significant surface modification and corresponding increases in the measured adhesion force. No statistically significant differences were found in either the run-in period length or the degradation rate between hot switching conditions and purely mechanical switching, microelectromechanical systems.
关键词： asperity contacts,surface hydrocarbons,hot switching,tribology,Adhesion,ambient air testing
更新于2025-09-04 15:30:14
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Topologically Nontrivial Valley States in Bilayer Graphene Quantum Point Contacts
摘要： We present measurements of quantized conductance in electrostatically induced quantum point contacts in bilayer graphene. The application of a perpendicular magnetic field leads to an intricate pattern of lifted and restored degeneracies with increasing field: at zero magnetic field the degeneracy of quantized one-dimensional subbands is four, because of a twofold spin and a twofold valley degeneracy. By switching on the magnetic field, the valley degeneracy is lifted. Because of the Berry curvature, states from different valleys split linearly in magnetic field. In the quantum Hall regime fourfold degenerate conductance plateaus reemerge. During the adiabatic transition to the quantum Hall regime, levels from one valley shift by two in quantum number with respect to the other valley, forming an interweaving pattern that can be reproduced by numerical calculations.
关键词： quantum point contacts,quantized conductance,valley degeneracy,bilayer graphene,Berry curvature
更新于2025-09-04 15:30:14