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Among transition metal oxides, MoO3 is a promising material due to its layered structure and different oxidation states, making it suitable for different device applications. One of the methods used to grow MoO3 is radio frequency magnetron sputtering (RFMS), which is the most compatible method in industry. However, obtaining nanostructures by RFMS for metal oxides is challenging because of compact morphology film formation. In this study, α-MoO3 with vertical nanowalls is obtained by a two-step process; deposition of magnetron-sputtered MoS2 vertical nanowalls and postoxidation of these structures without changing the morphology. In situ transmittance and electrical measurements are performed to control the oxidation process, which shed light on understanding the oxidation of MoS2 nanowalls. The transition from MoS2 to α-MoO3 is investigated with partially oxidized MoS2/MoO3 samples with different thicknesses. It is also concluded that oxidation starts from nanowalls perpendicular to the substrate and lasts with oxidation of basal planes. Four different thicknesses of α-MoO3 nanowall samples are fabricated for H2 gas sensors. Also, the effect of Pd deposition on the H2-sensing properties of sensors is deeply investigated. An outstanding response of 3.3 × 105 as well as the response and recovery times of 379 and 304 s, respectively, are achieved from the thinnest Pd-loaded sample. Also, the gas-sensing mechanism is explored by gasochromic measurements to investigate the sensor behaviors under the conditions of dry air and N2 gas as the carrier gas.

GaN-based materials are of great interest because of their potential applicability to produce both optoelectronic electronic devices such as high efficiency light emitting diodes (LEDs) [1], laser diodes (LDs) [2], and high-power and high-temperature electronic devices [3]. Such highperformance devices require state-of-the-art growth technologies such as molecular beam epitaxy (MBE) and metalorganic chemical vapor deposition (MOCVD). Although, it is difficult to grow high-quality GaN epilayers due to large lattice and thermal expansion mismatch between the sapphire substrate

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In the present work, Gallium Oxide (Ga2O3) were deposited as thin films by radio frequency (RF) magnetron sputtering at 300 °C substrate temperature on glass substrate using Ga2O3 target with 99.99% purity. The crystalline structure, morphology, optical properties of the Gallium Oxide films were determined using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-Visible Spectrometry, respectively. Experimental results show that annealing has an important role in the changes observed in the characterization of the Gallium Oxide thin films. All thin films produced were amorphous, except for the annealed P4-500. SEM pictures reveal the morphology of prepared Gallium Oxide thin films. The refractive index and real part of complex dielectric constant increased as the film deposition pressure increased.