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Epitaxial integration of superconductors with semiconductors is expected to enable new device architectures and to increase electronic circuit and system functionality and performance in diverse fields, including sensing and quantum computing. Herein, radiofrequency plasma molecular‐beam epitaxy is used to epitaxially grow 3–200 nm‐thick metallic NbNx and TaNx thin films on hexagonal SiC substrates...
Superconductors
Integration of superconductors with semiconductors is required for high‐performance electron devices in new quantum, sensing, and systems applications. In article number 1900675, D. Scott Katzer and co‐workers report the fully epitaxial integration of III‐N and GaN HEMT structures on superconducting transition metal nitrides. Image created by Robert Kurcoba using an atomic image provided...
Secondary-electron-emission current measured from high-purity, single-crystal CVD diamond is found to increase when 3.1-eV photons are incident on the hydrogenated surface. Energy spectra indicate that the sub-gap illumination causes the band levels to shift in the bulk, thereby reducing the upwards band bending at the pinned surface.
Quantum Efficiency from photocathodes and Yield from diamond secondary emitters are affected by scattering during electron transport in bulk material. The emission distribution is required to predict how current density and emittance from these sources affect beam transport in Particle-in-Cell codes, particularly MICHELLE. Monte Carlo is used to augment a standard Three-Step-Model (TSM) based model...
We report progress in mounting small thin diamond sheets over holes in larger substrates in a manner that allows electron beam amplification. In addition to a physical mount, our bonding method must be compatible with the creation and maintenance of the negative electron affinity surface and operation at elevated temperatures. We use a transient liquid phase bonding method wherein the constituent...
A diamond current amplifier is being developed that can be biased to generate an internal electric field needed for high transport efficiency and emission gain. In the process, a bonded diamond structure has been successfully fabricated that provides mechanical support for the microns-thick diamond film and that allows for the use of processing techniques needed to fabricate the biased device. Emission...
We present measurements of secondary electron emission obtained with a new NRL measurement system. This system allows us to measure in two orthogonal angular directions, the energy-dependent emission for different incident angles and beam energies.
Electron transport through thin film semiconductors is common to both the development of semiconductor photocathodes and to secondary emission electron sources. We discuss the modeling and numerical simulation of such transport in the presence of scattering and loss mechanisms, to enable predictive estimations of energy distributions, time response, and the nature of the distribution of the emitted...
Secondary-electron-emission measurements are used to examine the transport and emission characteristics of an 8.3-micron-thick diamond amplifier film. Superior transport and emission properties are confirmed for the single-crystal CVD diamond compared to previously-studied polycrystalline diamond. In particular, low-energy secondary electrons are emitted from the conduction band even after diffusing...
We report photoemission images of a GaN p-n junction patterned and etched to reveal both n-type and p-type regions. Immediately following Cs deposition at low temperature, the n-type areas produced more emission current than did the p-type areas and required only low energy (3 eV) photons to do so. After heating to 375°C the p-type areas became dominant when illuminated with high energy photons (4...
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