A gas sensor based on a ZnGa 2 O 4 (ZGO) thin film grown by metalorganic chemical vapor deposition operated under the different temperature from 25 °C to 300 °C is investigated in this study. This sensor shows great sensing properties at 300 °C. The sensitivity of this sensor is 22.21 as exposed to 6.25 ppm of NO and its response time is 57 s. Besides that, the sensitivities are 1.18, 1.27, 1.06, and 1.00 when exposed to NO 2 (500 ppb), SO 2 (125 ppm), CO (125 ppm), and CO 2 (1500 ppm), respectively. These results imply that the ZGO gas sensor not only has high sensitivity, but also has great selectivity for NO gas. Moreover, the obtained results suggest that ZGO sensors are suitable for the internet of things(IOT) applications.

ZnGaO films were grown on c-plane sapphire substrates by metal organic chemical vapor deposition using diethylzinc (DEZn), triethylgallium (TEGa), and oxygen. The flow rate of DEZn was 10–60 sccm, and those of TEGa and oxygen were held constant. The ZnGaO film prepared at a DEZn flow rate of 10 sccm adopted a (2̅01)-oriented single-crystalline β-Ga2O3 phase, whereas those prepared at 30–60 sccm exhibited a (111)-oriented single-crystalline ZnGa2O4 phase. On the basis of Hall measurements, ZnGaO films (10 sccm DEZn) possessed very poor electrical properties, which were similar to those of β-Ga2O3. On the other hand, the carrier concentration in ZnGaO films increased from 1.94 × 1014 to 6.72 × 1016 cm–3, and the resistivity decreased from 5730 to 67.9 Ω-cm when increasing the DEZn flow rate from 30 to 60 sccm. According to compositional analyses, the improved electrical properties of ZnGaO films upon increasing DEZn flow rate from 30 to 40 sccm are due to the increasing Zn content, and the enhancement from 50 to 60 sccm could be due to increased C content. Cathodoluminescence results also confirm the ZnGa2O4 structure for ZnGaO films prepared at DEZn flow rates of 30–60 sccm and reveal their use for ultraviolet applications.

Gallium nitride films, epitaxially grown on Si(111) via a lattice-matched ZrB(2) buffer layer by plasma-assisted molecular beam epitaxy, have been studied in situ by noncontact atomic force microscopy and also in real time by reflection high-energy electron diffraction. The grown films were determined to be always N-polar. First-principles theoretical calculations modeling the interface structure between GaN(0001) and ZrB(2)(0001) clarify the origin of the N polarity.

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In this study, defect analysis was conducted on ZnGa2O4 thin-film transistors of various thicknesses grown on sapphire substrates. The thickness of each ZnGa2O4 epilayer was controlled by adjusting its growth time. The electrical properties and physical characteristics were strongly related to epilayer thickness, which was also dependent on both crystallinity and the amount of oxygen vacancies in the thin film. Epilayer thickness was independent of thin-film surface roughness. The study demonstrated that an increase in the thickness of the epilayer can improve crystallinity and create more oxygen vacancies, which can serve as defect centers. If the epilayer is thin, then the film can be influenced by the dislocation of the epilayer from the sapphire substrate. The results suggests that the defects may occur because of crystallinity, oxygen vacancies, and dislocation of the ZnGa2O4 epilayer from the sapphire substrate. A ZnGa2O4 thin film with low resistance has high crystallinity and numerous oxygen vacancies. A trade-off exists between conductivity and defects in ZnGa2O4 epilayers. Moreover, the results demonstrate that conductivity in ZnGa2O4 epilayers is influenced more by the number of existing oxygen vacancies than by crystallinity. Two main regions trapping electrons, including the interface between the dielectric layer and ZnGa2O4 and the dislocation between ZnGa2O4 and the sapphire substrate, were proposed. The interfacial bonding configurations in ZnGa2O4 and sapphire heterostructures associated with different possible heterostructures were analyzed.