Enhanced charge transfer across the dual interface of Ga2O3@TiO2/Ti3C2 heterojunction for self-powered deep-ultraviolet photodetector

Fabricating heterojunctions between Ga2O3 and other materials facilitates the self-powering capabilities and improves the energy efficiency of deep-ultraviolet photodetector photodetectors. Herein, a dual built-in electric field is engineered at the junction of a 3D Ga2O3 nanowires network with 2D TiO2 and Ti3C2 nanosheets, enhancing the rapid charge transport under the self-powered mode. The optimal Ga2O3@TiO2/Ti3C2 heterostructure photodetector with suitable contents of TiO2 and Ti3C2 is constructed by spin coating 2D TiO2/Ti3C2 nanosheets on Ga2O3 nanowire-network, resulting in a self-powered responsivity of 18.90 mA W- 1 and a detectivity of 1.06 x 1012 Jones, which is attributed to the formed dual heterojunction interface. In addition, Ga2O3@TiO2/Ti3C2 shows the highest photo-to-dark current ratio (5199.00), responsivity (649.88 mA W-1), detectivity (1.48 x 1013 Jones), and external quantum efficiency (317.44 %) at 10 V bias, which are 3.99, 74.86, 17.30 and 74.86 times than pure MSM-type Ga2O3 nanowires photodetector. Ga2O3@TiO2/Ti3C2 photodetector also exhibits superior responsivity compared with Ga2O3@Ti3C2 photodetector, suggesting that the double builtin electric field enhances charge transfer more effectively than a single built-in electric field. Ga2O3@TiO2/Ti3C2 photodetector also exhibits good detection stability. Computational results, including charge density difference, work functions, and band structures, clarify the formation mechanism of dual built-in electric fields and highlight their crucial role in accelerating the separation and transfer of photogenerated electrons. These results highlight the effectiveness of developing dual built-in electric field heterojunction photodetectors in facilitating self-driven operation and improving photoelectric conversion efficiency.