Two-dimensional molybdenum ditelluride waveguide-integrated near-infrared photodetector

Abstract

Low-cost, small-sized, and easy integrated high-performance photodetectors for photonics are still the bottleneck of photonic integrated circuits applications and have attracted increasing attention. The tunable narrow bandgap of two-dimensional (2D) layered molybdenum ditelluride (MoTe₂) from ∼0.83 to ∼1.1 eV makes it one of the ideal candidates for near-infrared (NIR) photodetectors. Herein, we demonstrate an excellent waveguide-integrated NIR photodetector by transferring mechanically exfoliated 2D MoTe₂onto a silicon nitride (Si₃N₄) waveguide. The photoconductive photodetector exhibits excellent responsivity (R), detectivity (D*), and external quantum efficiency at 1550 nm and 50 mV, which are 41.9 A W^-1, 16.2 × 10¹⁰Jones, and 3360%, respectively. These optoelectronic performances are 10.2 times higher than those of the free-space device, revealing that the photoresponse of photodetectors can be enhanced due to the presence of waveguide. Moreover, the photodetector also exhibits competitive performances over a broad wavelength range from 800 to 1000 nm with a highRof 15.4 A W^-1and a largeD* of 59.6 × 10⁹Jones. Overall, these results provide an alternative and prospective strategy for high-performance on-chip broadband NIR photodetectors.

Keywords: infrared light; molybdenum ditelluride; photoconductive photodetector; silicon nitride waveguide; two-dimensional materials.