High-Speed Scalable Silicon-MoS₂ P-N Heterojunction Photodetectors

Two-dimensional molybdenum disulfide (MoS₂) is a promising material for ultrasensitive photodetector owing to its favourable band gap and high absorption coefficient. However, their commercial applications are limited by the lack of high quality p-n junction and large wafer scale fabrication process. A high speed Si/MoS₂ p-n heterojunction photodetector with simple and CMOS compatible approach has been reported here. The large area MoS₂ thin film on silicon platform has been synthesized by sulfurization of RF-sputtered MoO₃ films. The fabricated molecular layers of MoS₂ on silicon offers high responsivity up to 8.75 A/W (at 580 nm and 3 V bias) with ultra-fast response of 10 μsec (rise time). Transient measurements of Si/MoS₂ heterojunction under the modulated light reveal that the devices can function up to 50 kHz. The Si/MoS₂ heterojunction is found to be sensitive to broadband wavelengths ranging from visible to near-infrared light with maximum detectivity up to ≈1.4 × 10¹² Jones (2 V bias). Reproducible low dark current and high responsivity from over 20 devices in the same wafer has been measured. Additionally, the MoS₂/Si photodetectors exhibit excellent stability in ambient atmosphere.