Two-dimensional (2D) MoS2 is a representative n-type transition-metal dichalcogenide (TMD) semiconductor that has great potential for future nanoscale electronic and optoelectronic applications. Here, we report a high-performance MoS2 phototransistor that exhibits a photoresponse in the 400–700 nm range with the maximum responsivity of over 1 × 104 A/W. As a more sophisticated optoelectronic application than a simple unit device, it is implemented in a photoinverter (NOT logic gate) connected to an external resistor, which clearly shows photoinduced static and dynamic characteristics. Furthermore, we demonstrate a prototype visible imager using the MoS2 photoinverter as imaging pixels as an excellent example of advanced developments in an optoelectronic system based on the 2D semiconductors.

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Short-wave infrared (SWIR) detectors and emitters have a high potential value in several fields of applications, including the internet of things (IoT) and advanced driver assistance systems (ADAS), gas sensing. Indium Gallium Arsenide (InGaAs) photodetectors are widely used in the SWIR region of 1–3 μm; however, they only capture a part of the region due to a cut-off wavelength of 1.7 μm. This study presents an InAs p-i-n photodetector grown on a GaAs substrate (001) by inserting 730-nm thick In x Al 1−x As graded and AlAs buffer layers between the InAs layer and the GaAs substrate. At room temperature, the fabricated InAs photodetector operated in an infrared range of approximately 1.5–4 μm and its detectivity ( D * ) was 1.65 × 10 8 cm · Hz 1/2 · W −1 at 3.3 μm. To demonstrate performance, the Sherlock Holmes mapping images were obtained using the photodetector at room temperature.