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Transition metal dichalcogenides (TMDs) and their heterojunctions are drawing immense research interest for various applications including infrared detection. They are being studied with different semiconductor materials to explore their heterojunction properties. In this regard, we report a MoSe2/Si heterojunction broadband photodiode which is highly sensitive for a wide spectral range from 405 nm to 2500 nm wavelength with the maximum responsivity of ∼522 mA W−1 for 1100 nm of incident light. The hydrothermal synthesis approach leads to the imperfect growth of the MoSe2, creating defects in the lattice, which was confirmed by x-ray photo-spectroscopy. These sub-bandgap defects caused high optical absorption of the SWIR light as observed in the absorption spectra. The speed of the device ranges to 18/10 μs for 10 kHz modulated light. Furthermore, the photodetector has been fully operational even at zero bias voltage, making it a potential contender for self-powered photodetection. [ABSTRACT FROM AUTHOR]

Here, an optically pumped terahertz (THz) modulator based on the novel transition metal dichalcogenide (TMD) material platinum diselenide (PtSe2) is demonstrated. The nanostructured PtSe2 thin films are formed by direct selenization of the sputtered platinum film on a high‐resistivity silicon substrate. Raman spectroscopy, scanning electron microscopy, and high‐resolution transmission electron microscopy confirm the formation of polycrystalline PtSe2 nanostructures. The transmission measurements reveal the modulation of the THz waves in the wide frequency range of 0.1–1 THz. The modulation depth of 32.7% is achieved under low pumping laser power of 1 W cm−2. The numerical analysis based on the finite difference time domain method is in good agreement with the experimentally obtained results. Further, the simulation results manifest that higher modulation depth can be achieved with the utilization of higher laser power. This work provides a path for the application of TMD materials like PtSe2 in the development of THz tunable devices such as modulators, polarizers, filters. [ABSTRACT FROM AUTHOR]

A highly efficient room temperature photodetector with broadband (400 nm–1800 nm) photoresponse based on the MoSe2/Ge heterojunction has been reported here. The fabricated MoSe2/Ge heterojunction exhibits high responsivity up to 24 A/W in the near-infrared wavelength range (750 nm) and 35 A/W in the short wavelength infrared range (1550 nm). The interfacial charge transfer at the Ge-MoSe2 heterojunction enables self-powered photo-detection in fabricated devices with zero bias responsivity values of 250 mA/W (750 nm) and 400 mA/W (1550 nm). Transient photoresponse measurements of the MoSe2/Ge heterojunction under the modulated light reveal that the devices are capable of working up to 20 kHz with a fast rise/fall time of 13.5/1.2 μsec. These results demonstrate the feasibility of achieving a high-performance photodetector derived from the MoSe2/Ge heterojunction for broadband infrared detection. [ABSTRACT FROM AUTHOR]

This work presents the fabrication of a photodetector based on multiple WO3 nanowires for ultra-violet detection. This photodetector exhibits a photo-to-dark current ratio of the order of 4 with a high relative change in conductance around 8100 upon 340 nm illumination at 0.87 mW/cm2. The photodetector exhibits a high responsivity of 47.3 A/W and a high 340 nm–450 nm rejection ratio of ∼8800 with excellent stability. A low noise equivalent power of 0.37 fW/√Hz and a high detectivity of ∼1012 Jones are observed. We obtained a fast response with a rise time (tr) of 112 μs and a fall time (tf) of 84 μs. These promising results demonstrate the applicability of the photodetector for high speed ultra-violet detection. [ABSTRACT FROM AUTHOR]

A high speed efficient broadband photodetector based on a vertical n-MoS2/p-porous silicon heterostructure has been demonstrated. Large area MoS2 on electrochemical etched porous silicon was grown by sulphurization of a sputtered MoO3 thin film. A maximum responsivity of 9A/W (550–850 nm) with a very high detectivity of ~1014 Jones is observed. Transient measurements show a fast response time of ~9 μs and is competent to work at high frequencies (~50kHz). The enhanced photodetection performance of the heterojunction made on porous silicon over that made on planar silicon is explained in terms of higher interfacial barrier height, superior light trapping property, and larger junction area in the MoS2/porous silicon junction. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Transition metal dichalcogenides (TMDs) and their heterojunctions are drawing immense research interest for various applications including infrared detection. They are being studied with different semiconductor materials to explore their heterojunction properties. In this regard, we report a MoSe 2 /Si heterojunction broadband photodiode which is highly sensitive for a wide spectral range from 405 nm to 2500 nm wavelength with the maximum responsivity of ∼522 mA W -1 for 1100 nm of incident light. The hydrothermal synthesis approach leads to the imperfect growth of the MoSe 2 , creating defects in the lattice, which was confirmed by x-ray photo-spectroscopy. These sub-bandgap defects caused high optical absorption of the SWIR light as observed in the absorption spectra. The speed of the device ranges to 18/10 μs for 10 kHz modulated light. Furthermore, the photodetector has been fully operational even at zero bias voltage, making it a potential contender for self-powered photodetection.

Two-dimensional molybdenum disulfide (MoS 2 ) 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/MoS 2 p-n heterojunction photodetector with simple and CMOS compatible approach has been reported here. The large area MoS 2 thin film on silicon platform has been synthesized by sulfurization of RF-sputtered MoO 3 films. The fabricated molecular layers of MoS 2 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/MoS 2 heterojunction under the modulated light reveal that the devices can function up to 50 kHz. The Si/MoS 2 heterojunction is found to be sensitive to broadband wavelengths ranging from visible to near-infrared light with maximum detectivity up to ≈1.4 × 10 12 Jones (2 V bias). Reproducible low dark current and high responsivity from over 20 devices in the same wafer has been measured. Additionally, the MoS 2 /Si photodetectors exhibit excellent stability in ambient atmosphere.