Enhancement of responsivity and a self-powered on-chip LNOI integrated Bi₂Te₃ photodetector array

The topological insulator Bi₂Te₃ possesses an extraordinary optoelectronic property for wide-band optoelectronics device applications. In this study, we demonstrate a high responsivity and self-powered on-chip lithium niobate on insulator (LNOI) waveguide-integrated Bi₂Te₃ photodetector array operating at 1550 nm. Enhancement of responsivity is attributed to the decreased Bi₂Te₃/Au contact resistance, which is facilitated by electrothermal annealing. The post-electrothermal annealed on-chip photodetector was demonstrated a photocurrent response increased by four orders of magnitude, reaching as high as 5.5 µA. It features a photoresponsivity of 60 mA/W and a response time of 10 µs. The uniform performance of the fabricated Bi₂Te₃ photodetector arrays integrated with 4× multi-mode interference on the same LNOI photonic chips proves its potential for applications in high-efficiency optical communication, optical computing, and large-scale data processing.