Active pixel sensor matrix based on monolayer MoS2 phototransistor array

Abstract Development of low-power and smart vision sensors is critical for many emerging applications including the acceleration of edge intelligence. In this article, we introduce an active pixel sensor (APS) technology with in-sensor compute capability based on atomically thin two-dimensional (2D) semiconducting material such as monolayer MoS2. The presented 2D APS uses only one programmable phototransistor (1T cell), which significantly reduces the area overhead allowing one to fit 900 pixels in ~0.09 cm2. Phototransistors in the array exploit gate tunable persistent photoconductivity to exhibit high responsivity (~3.6×107 A/W), high specific detectivity (~5.6×1013 Jones), spectral uniformity, and high dynamic range (~80 dB) and electrical programmability to achieve fast reset (~ 100 µs) and in-sensor de-noising capabilities. Commonly encountered problems in the field of 2D material based vision sensors are also resolved by showing near-ideal yield and low device-to-device variation in photoresponse owing to high quality growth, damage-free transfer, and relatively clean fabrication process flow. Remarkably, the energy expenditure by 2D APS was found to be miniscule and in the range of hundreds of femto Joules per pixel. We believe, our low-power 2D APS technology with in-sensor image processing capabilities can be transformative for many edge applications.