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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.

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p-Si/n-CdS radial heterojunction nanowires have been grown by pulse laser deposition of CdS on vertically aligned Si nanowires fabricated using a room temperature wafer-scale etching of p-type Si. Temperature-dependent photoluminescence characteristics have been studied in detail in the blue−green−red regions from these p-Si/n-CdS core−shell nanowires. The photocurrent spectra of the nanowire heterojunctions have been investigated at room temperature to study the spectral responsivity and detectivity of the core−shell nanowire diodes. The peak responsivity (1.37 A/W) and detectivity (4.39 × 10 11 cm Hz 1/2 /W) at −1 V show the potential of the nanoscaled devices for the high efficiency photodetectors in the visible− near-infrared spectrum.