Performance of Topological Insulator (Sb₂Te₃)-Based Vertical Stacking Photodetector on n-Si Substrate

— In this work, we report the photodetector properties of a vertically stacked heterostructure based on topological insulator Sb₂Te₃/n-Si. The high-quality Sb₂Te₃ thin films were grown on an n-Si substrate by the metal–organic chemical vapor deposition (MOCVD) technique. The fabricated Sb₂Te₃/n-Si heterostructure devices promise to work as an excellent rectification diode with an excellent rectification ratio (RR) (351.4 at ±3 V), under dark condition. The device shows remarkable photoresponse at a broad spectral near-infrared range of between 700 and 1100 nm. The maximum responsivity and detectivity of Sb₂Te₃/n-Si heterojunction diode 1600 mA/W and 7.48 × 10¹⁰ Jones (at +3 V) were observed at 900-nm wavelength of incident light. The electronic and optical properties of the Sb₂Te₃ are evaluated using first-principle calculations based on density functional theory (DFT). The bandgap of Sb₂Te₃ was found to be 0.12 eV. The optical properties of Sb₂Te₃ were calculated based on DFT and random phase approximation. The absorption coefficient shows that Sb₂Te₃ absorbed the light in a broadband spectral region and maximum absorption at 905 nm, which is in good agreement with the experimental results.