Structure design of bilayer MoS 2 image sensor array The proposed active pixel image sensor array can potentially be used for future image-sensing applications, such as ultra-thin image sensors, transparent image sensors, artificial-intelligence photosensors, and selective light-detecting imagers 29, 30, 31, 32.

Finally, we demonstrate the image-sensing characteristics of the active pixel image sensor array using light stencil projection. It is revealed that the 64 individual pixels exhibit desired electrical and optical properties and high uniformity. Moreover, both the 64 switching transistors and the 64 phototransistors based on homogeneous semiconductor (i.e., bilayer MoS 2) in the 8 × 8 active pixel array are systematically investigated. The simulations highlight the correlation between threshold voltage ( V th) shift and high R ph when including subgap states near the valence band edge. This explanation is supported by spectroscopic analysis and by numerical device simulations. The main mechanism responsible for the high photoresponsivity of the bilayer MoS 2 phototransistor is the photogating (PG) effect induced by light-generated holes trapped at subgap states. The phototransistor used as a photodetector in the active pixel image sensor achieves a remarkably high photoresponsivity ( R ph) and signal-to-noise ratio (SNR). The circuitry in 8 × 8 active pixel image sensor array consists of switching transistors and phototransistors. In this study, we report on an active pixel image sensor array with a large-area bilayer MoS 2 film, which was directly synthesized on a SiO 2/Si substrate via a two-step growth method consisting of MoS 2 sputtering (first step) and sulfurization (second step) without any transfer process. Large-scale growth methods for TMDs have been reported, but they have not yet been employed to synthesize active pixel image sensors, which are integrated circuits consisting of photodetectors and active transistors that can detect the incident image light and convert it into digital image signals 26, 27, 28. 24 reported a curved single photodetector array based on MoS 2-graphene synthesized via CVD. 23 reported inverter arrays based on wafer-scale MoS 2 synthesized via atomic layer deposition (ALD). 22 reported a full-color active-matrix organic light-emitting diode display based on large-area MoS 2 synthesized via metal–organic chemical vapor deposition (CVD). By contrast, various large-area growth methods for 2D TMDs have been developed for future electronic and photonic applications 18, 19, 20, 21, 22, 23, 24, 25. However, although the TMD flakes obtained via mechanical exfoliation exhibit unique properties, their use in large-scale practical applications is difficult due to their low reproducibility and large property variations 10, 11, 12, 13, 14, 15, 16, 17. Two-dimensional (2D) transition metal dichalcogenides (TMDs) such as molybdenum disulfide (MoS 2), molybdenum diselenide (MoSe 2), tungsten disulfide (WS 2), and tungsten diselenide (WSe 2) have been extensively studied as next-generation semiconducting materials due to their attractive electrical and optical properties 1, 2, 3, 4, 5, 6, 7, 8, 9. The image-sensing characteristics of the bilayer MoS 2 active pixel image sensor array are successfully investigated using light stencil projection. With the aid of computational modeling, we find that the main mechanism for the high R ph of the bilayer MoS 2 phototransistor is a photo-gating effect by the holes trapped at subgap states.

The maximum photoresponsivity ( R ph) of the bilayer MoS 2 phototransistors in an 8 × 8 active pixel image sensor array is statistically measured as high as 119.16 A W −1.

The active pixel of image sensor is composed of 2D MoS 2 switching transistors and 2D MoS 2 phototransistors. Here, we report on an active pixel image sensor array with a bilayer MoS 2 film prepared via a two-step large-area growth method. However, they have not yet been employed for synthesizing active pixel image sensors. Various large-area growth methods for two-dimensional transition metal dichalcogenides have been developed recently for future electronic and photonic applications.

Pixel 3 portal 2 image