High Crystalline Quality Ta-Doped <i>h</i>-ZnTiO₃ Epitaxial Films: Characteristics and Application in UV Detectors

Ta-doped h-ZnTiO3 (h-ZnTiO3:Ta) films with an atomic ratio of 0–5% are grown on sapphire substrates by pulsed laser deposition. The prepared films exhibit n-type semiconductor behavior with high epitaxial crystalline quality. These films have high transparency, and their optical band gaps exceed 3.72 eV. The Hall mobility and carrier concentration of the 1% Ta-doped film are 4.6 cm2/(V·s) and 4.20 × 1014 /cm3, respectively. The h-ZnTiO3:Ta film-based metal–semiconductor–metal (MSM) photodetectors are fabricated, and their characteristics are analyzed in detail. Among them, 1% Ta-doped h-ZnTiO3 film-based devices show the best detection performance, including responsivity of 4.23 mA/W and detectivity of 1.43 × 1011 Jones, under the wavelength of 308 nm ultraviolet light with an optical density of 140 μW/cm2. The detector also has an extremely fast response time (rise time: 0.16 s and fall time: 0.04 s). This work proves that h-ZnTiO3:Ta epitaxial films have great application prospects in future optoelectronic devices.