Efficient Photothermal and Photocurrent Enhancements in Bi₂Te₃ Topological Insulator Nanofilm by Integrating with a Photonic Crystal

Bismuth telluride (Bi₂Te₃) topological insulator (TI) presents excellent photothermoelectric characteristics with promising applications in photonic detection, catalysis, and sensing. Exploring effective approaches to enhance the photothermal and photocurrent response in the Bi₂Te₃ TI films is particularly significant for improving the photodetection capacity. Herein, the generation of an optical effect analogous to Tamm plasmons is experimentally and numerically demonstrated by integrating the Bi₂Te₃ TI nanofilm onto a 1D photonic crystal (PC). The Bi₂Te₃/PC multilayer enables the distinct enhancement of near-infrared light absorption and photothermal effect of Bi₂Te₃ nanofilm based on the TI-based optical Tamm state. The measured results reveal that the reflection spectrum of Bi₂Te₃ nanofilm on the PC exhibits a distinct dip, whose position has a redshift with increasing the thickness of Bi₂Te₃ film. The numerical and theoretical calculations agree well with the experiments. The reflection dip stems from the formation of the TI-based Tamm state, whose wavelength exhibits a slight blueshift with the increase of temperature. The zero-bias photocurrent conversion of Bi₂Te₃ nanofilm can be obviously self-reinforced with impinging light on the Bi₂Te₃/PC structure at the Tamm state wavelength. The results pave a new avenue for enhancing light-TI interactions and their applications in high-performance near-infrared photodetection devices.