Large-scale free-standing Bi2Te3/Si heterostructures developed by a modified solvothermal method for a self-powered and efficient imaging photodetector

Topological insulator bismuth telluride (Bi2Te3), an exotic state of quantum matter, has broad application prospects in next-generation optoelectronic devices. However, photoexcited carriers in Bi2Te3 usually relax rapidly due to the lack of a large band gap. Herein, high-quality Bi2Te3/Si heterojunction is successfully synthesized by a low-cost modified two-step solvothermal method to grow large-scale free-standing Bi2Te3 nanosheets on a Si substrate. Benefiting from the promotion of photogenerated carrier separation and transport by the built-in electric field at the Bi2Te3/Si heterojunction interface, the Bi2Te3/Si heterojunction photodetector exhibits a high responsivity of 16.44 mA W−1, a high specific detectivity of 2.44 × 1011 Jones, and fast rise/recovery times of 11/13 ms under 470 nm illumination at zero bias. Additionally, the device has potential applications in high-resolution imaging. In view of its overall photosensitivity performance and low cost, the Bi2Te3/Si heterojunction synthesized by the solvothermal method has a promising application in fast broadband photodetectors, and also provide a new route for the growth of Bi2Te3 nanosheets on substrates. [Display omitted] •Bi2Te3/Si heterostructures were developed by a modified low-cost solvothermal method.•An MSM-type photodetector was constructed based on the Bi2Te3/Si heterostructures.•The separation and transport of photogenerated carriers are promoted.•The photodetector exhibits excellent response performance under 0 V bias.•The stable imaging capacity of the photodetector is demonstrated.