Fabrication and characterization of ultraviolet detector based on epitaxial Ta-doped Zn2SnO4 films

Abstract Zn2SnO4 films with Ta concentrations from 0 to 5% were deposited on MgO(100) substrates via pulsed laser deposition, and annealed in air atmosphere at 800 °C. The structure, surface morphology, optical and electrical properties of the films were systematically studied. The obtained films were inverse-spinel phase Zn2SnO4 grown along [100] orientation and the crystal quality decreased with Ta content. All the Ta-doped Zn2SnO4 films exhibited high average transmittances of about 95% in visible region with optical band gaps ranging from 3.98 to 4.10 eV. The metal-semiconductor-metal ultraviolet (UV) detector fabricated using the 3% Ta-doped Zn2SnO4 film exhibited the best detection performance with high photoresponsivity in wavelength range of 200–280 nm. The photoresponsivity at 254 nm was 23.3 A/W and the photo-dark current ratio exceeded 104 at 5 V bias. The Zn2SnO4-based detectors also showed good repeatability of UV detection.