Topological Insulator Bi₂Se₃/Si-Nanowire-Based p-n Junction Diode for High-Performance Near-Infrared Photodetector

Chemically derived topological insulator Bi₂Se₃ nanoflake/Si nanowire (SiNWs) heterojunctions were fabricated employing all eco-friendly cost-effective chemical route for the first time. X-ray diffraction studies confirmed proper phase formation of Bi₂Se₃ nanoflakes. The morphological features of the individual components and time-evolved hybrid structures were studied using field emission scanning electron microscope. High resolution transmission electron microscopic studies were performed to investigate the actual nature of junction whereas elemental distributions at junction, along with overall stoichiometry of the samples were analyzed using energy dispersive X-ray studies. Temperature dependent current-voltage characteristics and variation of barrier height and ideality factor was studied between 50 and 300 K. An increase in barrier height and decrease in the ideality factor were observed with increasing temperature for the sample. The rectification ratio (I₊/I_-) for SiNWs substrate over pristine Si substrate under dark and near-infrared (NIR) irradiation of 890 nm was found to be 3.63 and 10.44, respectively. Furthermore, opto-electrical characterizations were performed for different light power intensities and highest photo responsivity and detectivity were determined to be 934.1 A/W and 2.30 × 10¹³ Jones, respectively. Those values are appreciably higher than previous reports for topological insulator based devices. Thus, this work establishes a hybrid system based on topological insulator Bi₂Se₃ nanoflake and Si nanowire as the newest efficient candidate for advanced optoelectronic materials.