Gallium oxide (Ga₂O₃) films were deposited on singlecrystalline sapphire (0001) substrate by radio frequency (RF) magnetron sputtering technique in the temperature range of 300—500 °C. The microstructure of the β-Ga₂O₃films were investigated in detail using X-ray diffractometer (XRD) and scanning electron microscope (SEM). The results show that the film prepared at 500 °C exhibits the best crystallinity with a monoclinic structure (β-Ga₂O₃). Structure analysis reveals a clear out-of-plane orientation of β-Ga₂O₃(201) || Al₂O₃(0001). The average transmittance of these films in the visible wavelength range exceeds 90%, and the optical band gap of the films varies from 4.68 eV to 4.94 eV which were measured by an ultraviolet-visible-near infrared (UV-vis-NIR) spectrophotometer. Therefore, it is hopeful that the β-Ga₂O₃film can be used in the UV optoelectronic devices.

Indium oxide (In₂O₃) films were prepared on Al₂O₃(0001) substrates at 700 °C by metal-organic chemical vapor deposition (MOCVD). Then the samples were annealed at 800 °C, 900 °C and 1 000 °C, respectively. The X-ray diffraction (XRD) analysis reveals that the samples were polycrystalline films before and after annealing treatment. Triangle or quadrangle grains can be observed, and the corner angle of the grains becomes smooth after annealing. The highest Hall mobility is obtained for the sample annealed at 900 °C with the value about 24.74 cm²·V^-1·s^-1. The average transmittance for the films in the visible range is over 90%. The optical band gaps of the samples are about 3.73 eV, 3.71 eV, 3.70 eV and 3.69 eV corresponding to the In2O3 films deposited at 700 °C and annealed at 800 °C, 900 °C and 1 000 °C, respectively.

Flexible TiO₂ memory devices are fabricated on a plastic substrate at room temperature. The metal-insulator-metal (MIM) structure is grown on polyimide (PI). Several metals with different ductilities, such as Al, W, Cu and Ag, are selected as electrode. The test results show that the samples have stable resistive switching behaviors, and the electric characteristics can stay stable even after the radius of substrate is bent up to 10 mm. After 10³times of substrate bending, the memory cells with W as bottom electrode on PI still show stable resistive switching characteristics and low switching voltages. The set voltage and reset voltage can be as low as 0.9 V and 0.3 V, respectively.