Plasmon resonance enhanced WS2 photodetector with ultra-high sensitivity and stability

Tungsten disulfide (WS₂) has been demonstrated for optoelectronic devices due to its favorable semiconducting band gaps, high stability and higher carrier mobility than other transition metal dichalcogenides (TMDs). However, the photoresponsivity of WS₂-based photodetector is low due to the poor optical absorbance, which limits its application in high-performance photodetection. Here, we show an easy realized method to improve the responsivity of WS₂ detectors by Au nanospheres (NPs). The Au NPs concentrate free space electromagnetic wave efficiently by localized surface plasmon resonances (LSPR), strongly enhance the electric field on WS₂ films. As a result, more carriers are excited with the assistant of LSPR. With optimized design, the detector exhibited several times to ten folds enhancement from near infrared to visible spectrum region, and reach an excellent high responsivity of 1050 A/W at the wavelength of 590 nm. Furthermore, the photodetector showed an excellent temperature stability after annealing at 300 ^°C on air environment. The work provides a new way for high-performance and stable photodetector for extreme and harsh environment.