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The development of high-power millimeter and THz-band vacuum microelectronic devices (μVEDs) demands structural materials with special properties. In particular, key components of μVEDs must retain their dimensions when heated while operating at higher power levels. A molybdenum-copper alloy is a promising material, thanks to the low thermal expansion of molybdenum and the remarkable thermal and electrical conductivity of copper. However, such alloys can only be obtained by a limited number of techniques that are rather complicated. Thus, the goal of this work is the implementation of vacuum magnetron co-deposition as a facile method in the fabrication of μm-thick Mo–Cu films. Such films are very promising for the microfabrication of microstrip slow-wave structures for high-power millimeter and THz-band μVEDs. This study is focused on controlling the morphology, resistivity, and roughness of the fabricated thin films by changing the deposition process parameters, such as the sputtered Cu and Mo ratio and substrate temperature. [ABSTRACT FROM AUTHOR]

For high-power and compact sub-terahertz (THz) sources, a high-current electron beam is a crucial component. In this article, a miniaturized sheet-electron-beam source has been developed for generation of the high-current-density electron beam. It consists of a hollow cathode with a 3-mm diameter circular aperture, an anode with a 1.25 mm $\times0.25$ mm rectangular aperture, and an interelectrode three-gap region with optimized dimension. The developed electron beam source has been operated in self-breakdown conditions for applied gap voltage ranging between 10 and 30 kV. The sheet electron beam has been successfully propagated for nearly 45 mm inside the drift space without the assistance of an external magnetic field due to the space charge neutralization effect. It has demonstrated good transmission characteristics with more than 50-A beam current and beam current loss of around 25%. [ABSTRACT FROM AUTHOR]

Ongoing active development of modern radio frequency electronic devices operating in the millimeter (V) band, such as fifth-generation wireless communications, demands new materials to control electromagnetic interference, compatibility, and reliability of such systems. This work investigates feasibility absorptive non-reflective thin coatings deposition on dielectric substrates using simultaneous magnetron co-deposition. For this, electromagnetic waves propagation in the millimeter band through in micrometer-thick Al–Si films of varied composition was studied. The co-deposition process was controlled by the ratio of sputtered atoms fluxes. Graded segregation was observed under certain parameters of the co-deposition process, resulting in a depth gradient of an aluminum content, as confirmed by the secondary ion mass spectrometry study. A qualitative model was proposed involving aluminum-induced silicon recrystallization happening in the course of a known aluminum interlayer exchange process. The observed Al–Si segregation effect in micrometer-thick films allows for preparation of the non-reflective and absorptive material for operation in the V-band with reflection losses more than 10 dB and transmission losses around 5 dB in the bandwidth of up to 20 GHz. [ABSTRACT FROM AUTHOR]

We report the results of the design, simulation, fabrication, and cold-test measurements of millimeter-band 2D planar microstrip slow-wave structures (SWSs) on dielectric substrates. Such structures have a high slow-wave factor, which allows for low-voltage operation and reduction in the size and weight of the device. A low-cost and flexible fabrication technology based on magnetron sputtering and subsequent laser ablation has been developed and is reported in the paper. Microstrip meander-line SWS circuits at V-, W-, and D-bands have been fabricated and characterized. The fabrication of ring-bar planar SWSs by the photolithographic method is also discussed. Experimental measurement of S-parameters of the fabricated structures reveals good transmission properties. Return loss (S11) does not exceed −10 dB and attenuation is about 2 dB/cm in the V-band, 10 dB/cm in the W-band, and 8.5 dB/cm in the D-band. [ABSTRACT FROM AUTHOR]

The aim of this work is to discuss the possibility of resistive thin-film coatings used for vacuum electron devices. Following a short review, results on radiophysical parameters studies in millimeter-band of such coatings are presented. Resistive Sn-O coatings with varied oxygen content were fabricated on quartz substrates by reactive magnetron sputtering. Morphology and elemental composition of prepared coatings were studied by means of scanning electron microscopy and secondary ion mass spectrometry, while four-probe method was utilized to study the resistivity of those. Dielectric properties were measured in the V-band (50-70 GHz) in free space using vector network analyzer. It was demonstrated that resistivity and the dielectric properties of coating in millimeter-band can be widely varied by controlling coating composition. [ABSTRACT FROM AUTHOR]

Slow-wave structure (SWS) is a core part of a traveling-wave-tube (TWT) amplifier. In this letter, the planar microstrip meander SWS on a dielectric substrate at $V$ -band (50–70 GHz) is studied. The basic electromagnetic parameters of the SWS are calculated. The SWS circuits are designed and fabricated, and good transmission characteristics are measured. The SWS developed is characterized by a wide bandwidth and a relatively-large slow-wave factor, and is suitable for a low-voltage TWT with the sheet electron beam. [ABSTRACT FROM AUTHOR]

Technology for thin polycrystalline silicon films preparation is crucial for development of novel semiconductor devices, including flexible electronics. A method for thin polycrystalline silicon film preparation utilizing deposited nickel absorption layer which allows use of inexpensive 1064 nm pulsed YAG:Nd laser for laser annealing of magnetron‐sputtered amorphous silicon is reported here. Film morphology changes are visualized with scanning electron microscopy, its chemical composition and Ni fate upon laser irradiation are studied using X‐ray energy dispersion analysis and secondary ion mass spectrometry. Silicon crystalline structure changes and its homogeneity are characterized using Raman spectroscopy utilizing mapped spectral measurements. Range of laser radiation energy fluence (J cm−2) is established which allowed for preparation of fully polycrystalline silicon film with crystalline silicon Raman peak position and width comparable to that of single‐crystalline material. Nickel film is found to ablate substantially upon irradiation, leaving remains that can be easily removed by chemical etching. [ABSTRACT FROM AUTHOR]