Large‐Area Bi ₂ Te ₃ Flakes on Si‐Based Substrates for Sensitive IR Imaging Photodetection at MWIR Optical Communication Wavelengths

Abstract The monolithic integration of photodetectors for infrared optical communication wavelengths on Si‐based integrated circuits is of vital significance in modern commercial and military communication applications. Owing to its narrow bandgap, Bi ₂ Te ₃ has considerable potential in infrared photodetection. However, realizing its direct growth and large‐size monolithic integration on Si‐based substrates is a great challenge, which leaves ample room for improving its performance and application at infrared optical communication wavelengths. In this work, submillimeter Bi ₂ Te ₃ flakes are directly synthesized on SiO ₂ /Si substrates, subjected to argon plasma pretreatment to remove pollutants and activate the surface. After pretreatment for 3 min, this approach produced a suitable nucleation density and the largest lateral size of the flakes, reaching 0.16 mm. Furthermore, a Bi ₂ Te ₃ field‐effect transistor (FET) exhibited a competitive on/off ratio of 1.4 × 10 ⁶ and a mobility of 107.4 cm ² V ⁻¹ s ⁻¹ . The Bi ₂ Te ₃ photodetector shows considerable responsivity and detectivity values (5.21 A W ⁻¹ and 7.52 × 10 ¹² Jones at 1550 nm, 0.26 A W ⁻¹ and 2.74 × 10 ¹¹ Jones at 2275 nm), as well as excellent infrared imaging capabilities. This work not only provides guidance for optimizing the integration of 2D materials on Si‐based substrates, but also highlights the great potential of 2D Bi ₂ Te ₃ in infrared photodetection and communication.