The impact of metal contacts on the electrical properties of SiN dielectric film in MEMS capacitors is investigated. The investigation is performed employing MIM and MEMS capacitors with Au and Ni contacts. A resistive switching like behaviour is monitored in the case of Ni contacts. This behaviour is attributed to the presence of deep traps in SiN and the effect of different metal contacts as revealed from Thermally Stimulated Depolarization Current (TSDC) assessment. Specifically, TSDC showed that the resistive switching is a contact/interface dominated effect.

Abstract An isotype heterojunction n+-ZnO/n-Si photodetector is developed, showing adjustable wavelength-selective operation at self-powered conditions. Without an external bias voltage, the device can operate either as a broadband UV–vis–NIR or as a NIR-only photodetector, depending on the relative carrier concentrations of ZnO and silicon. In addition, the photodetector can be tuned to either broadband or NIR operation by the application of an external bias voltage, regardless of carrier concentrations. At negative bias, it demonstrates UV–vis–NIR photodetection, while at positive bias, NIR photodetection. Photovoltage and photocurrent measurements for pulsed illumination reveal a high-speed self-powered response, with rise and fall times <100 µs across the UV–vis–NIR. The device can be engineered to reproduce undistorted pulsed light with frequencies as high as 1 kHz. Self-powered responsivity reaches ≈70 mA W−1, which becomes ≈4 A W−1 with an applied external bias.

We perform a theoretical investigation of the electron–surface optical phonon (SOP) interaction in Van der Waals heterostructures (vdWHs) formed by monolayer graphene (1LG) and transition metal dichalcogenides (TMDCs), using eigenenergies obtained from the tight-binding Hamiltonian for electrons. Our analysis reveals that the SOP interaction strength strongly depends on the specific TMDC material. TMDC layers generate localized SOP modes near the 1LG/TMDC interface, serving as effective scattering centers for graphene carriers through long-range Fröhlich coupling. This interaction leads to resonant coupling of electronic sub-levels with SOP, resulting in Rabi splitting of the electronon energy levels. We further explore the influence of different TMDCs, such as WS2, WSe2, MoS2, and MoSe2, on transport properties such as SOP-limited mobility, resistivity, conductivity, and scattering rates across various temperatures and charge carrier densities. Our analysis confirms that at elevated temperatures and low carrier densities, surface optical phonon scattering becomes a dominant factor in determining resistivity. Additionally, we investigate the Auger recombination process at the 1LG/TMDC interface, showing that both Auger and SOP scattering rates increase significantly at room temperature and higher, ultimately converging to constant values as the temperature rises. In contrast, their impact is minimal at lower temperatures. These results highlight the potential of 1LG/TMDC-based vdWHs for controlling key processes, such as SOP interactions and Auger recombination, paving the way for high-performance nanoelectronic and optoelectronic devices.

Heterojunction formation between BiVO4 nanomaterials and benchmark semiconductor photocatalysts has been keenly pursued as a promising approach to improve charge transport and charge separation via interfacial electron transfer for the photoelectrocatalytic degradation of recalcitrant pharmaceutical pollutants. In this work, a heterostructured TiO2/Mo-BiVO4 bilayer photoanode was fabricated by the deposition of a mesoporous TiO2 overlayer using the benchmark P25 titania catalyst on top of Mo-doped BiVO4 inverse opal films as the supporting layer, which intrinsically absorbs visible light below 490 nm, while offering improved charge transport. A porous P25/Mo-BiVO4 bilayer structure was produced from the densification of the inverse opal underlayer after post-thermal annealing, which was evaluated on photocurrent generation in aqueous electrolyte and the photoelectrocatalytic degradation of the refractory anti-inflammatory drug ibuprofen under back-side illumination by visible and UV–Vis light. Significantly enhanced photoelectrochemical performance on both photocurrent density and pharmaceutical degradation was achieved for the bilayer structure with respect to the additive effect of the constituent layers, which was related to the improved light harvesting arising from the backscattering by the mesoporous TiO2 layer in combination with the favorable charge transfer at the TiO2/Mo-BiVO4 interface.