Optoelectronic insights into topological insulator Bi₂Se₃/Si heterojunction for photocurrent generation

Topological insulators are distinctive materials characterized by insulating bulk and metallic surface states that are topologically protected. Their comparatively low band gaps permit improved optical absorption across a wider wavelength spectrum, making them an excellent choice for broadband photodetection. This work focuses on the optoelectronic properties of an efficient photodetector utilizing Bi₂Se₃ TI film with Si substrate (111), for high-performance photodetector fabrication. One of the PVD techniques was employed to ensure minimum grain boundaries and homogeneous film growth. The structural characteristics of the Bi₂Se₃ were analyzed using x-ray diffraction, confirming impurity-free deposition. The electrical measurement of the Bi₂Se₃/Si heterojunction was examined by I-V measurements, indicating diode formation with a high rectification ratio and an apparent figure of merit. A two-diode simulation is used to replicate the experimental outcomes. Ideality factor-voltage (n-V) and Current density-voltage graph of fabricated heterojunctions were analyzed for recombination current. To evaluate the performance, a photodiode was successfully fabricated, demonstrating a superior photocurrent and impressive photoresponse, offering a cost-effective broadband detector and tremendous potential for optoelectronic applications.