Modulation of oxygen vacancies in InSnZnO thin films and applications for high-speed metal-semiconductor-metal ultraviolet photodetectors

Enhancing the response speed of photodetectors is of great significance, for meeting the requirements of high-density optical arrays and integration. Wide bandgap indium oxide with high electron mobility makes it suitable for the preparation of high-speed response ultraviolet photodetectors. Nevertheless, oxide semiconductor is prone to form oxygen vacancies during the growth process, leading to persistent photoconductivity in photodetectors, which considerably limits the practical application in ultraviolet detection. In this work, a well-performing metal–semiconductor-metal structure ultraviolet photodetector based on amorphous indium-tin-zinc-oxide was fabricated via co-sputtering technique. By enhancing the oxygen ratio during the co-sputtering, the concentration of oxygen vacancies was effectively reduced, which modulated the performances of the photodetector. This approach not only shortened the photodetector's response time but also omitted the annealing step, enabling a room-temperature fabrication process. As a result, the optimized indium-tin-zinc-oxide photodetector of 30 % oxygen exhibited remarkably rapid response characteristics under 367 nm ultraviolet irradiation, with rise and decay times of 0.018 and 0.066 s, respectively. Simultaneously, the optimized indium-tin-zinc-oxide phototransistor exhibited exceptional performance metrics, including a high photoresponsivity of 480 A/W, a detectivity of 3.2 × 1012 Jones and an external quantum efficiency of 1336 % under 367 nm ultraviolet irradiation with 1 mW/cm2 light intensity.