Self-powered photodetectors based on Er-doped MoS2 film for NIR photo-communication and laser calibration

Abstract

Molybdenum disulfide (MoS2) is a promising two-dimensional material for optoelectronic applications owing to its strong light–matter interactions, high carrier mobility, and ability to combine with other materials. However, the intrinsic bandgap (1.3–1.8 eV) of MoS2 limits its applications in the near-infrared (NIR) region. Herein, a heterojunction NIR photodetector based on the Er-doped MoS2 film is developed. The photodetector presents self-powered NIR response with a fast rise/fall time of ∼9.2 μs/∼168 μs and a high detectivity of ∼3.25 × 1010 Jones at 980 nm. The high performance of the device is attributed to the improved separation of the photogenerated electron–hole pairs and the characteristic trapping capacity induced by Er dopants. Density functional theory calculations reveal that Er-doping introduces an additional energy level in the forbidden band of the MoS2:Er, and the Er-f electron orbital locates near its Fermi energy level, both of which contribute to the formation of photogenerated carriers. The MoS2:Er-based device with a 3-dB bandwidth of 5.4 kHz exhibits promising application potential in the NIR photo-communication field. Moreover, the laser calibration application of the high-performance photodetector is demonstrated. This work not only develops an effective strategy to enhance the NIR photoresponse of MoS2 films but also extends the application of MoS2-based devices.