The last few decades faced on the fabrication of advanced engineering materials involving also different composites. Here, we report on the fabrication of few-layer molybdenum disulfide on top of thin polycrystalline diamond substrates with a high specific surface area. In the method, pre-deposited molybdenum coatings were sulfurized in a one-zone furnace at ambient pressure. As-prepared MoS2 layers were characterized by several techniques including grazing-incidence wide-angle X-ray scattering, atomic force microscopy, scanning electron microscopy, Raman spectroscopy and X-ray photoelectron spectroscopy. We found out that the initial thickness of Mo films determined the final c-axis crystallographic orientation of MoS2 layer as previously observed on other substrates. Even though it is well-known that Mo diffuses into diamond at elevated temperatures, the competing sulfurization applied effectively suppressed the diffusion and a chemical reaction between molybdenum and diamond. In particular, a Mo2C layer does not form at the interface between the Mo film and diamond substrate. The combination of diamond high specific surface area along with a controllable layer orientation might be attractive for applications, such as water splitting or water disinfection.

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The piezoelectric response of AlGaN/GaN circular HEMT pressure sensing device integrated on AlGaN/GaN diaphragm was experimentally investigated and supported by the finite element method modeling. The 4.2 μm thick diaphragm with 1500 μm diameter was loaded by the dynamic peak-to-peak pressure up to 36 kPa at various frequencies. The piezoelectric charge induced on two Schottky gate electrodes of different areas was measured. The frequency independent maximal sensitivity 4.4 pC/kPa of the piezoelectric pressure sensor proposed in a concept of micro-electro-mechanical system was obtained on the gate electrode with larger area. The measurement revealed a linear high performance piezoelectric response in the examined dynamic pressure range.

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