High Crystalline Quality Ta-Doped h-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.