HKUST Engineering Develops Van Der Waals-Integrated Image Sensor Technology For Ultralow-Power Near-Infrared Imaging
Prof. Zhengtang LUO, Professor of the Department of Chemical and Biological Engineering at HKUST, and his team have developed a van der Waals (vdWs)-integrated image sensor for ultralow-power imaging under near-infrared illumination. Their breakthrough uses crossbar array architecture consisting of vertical 1T’/2H-MoTe2/ITO devices, which results in atomic-scale channels and large illumination areas for self-powered photodetection with high photoresponsivity.
Conventional silicon-based image sensors suffer from high power consumption and a relatively narrow spectral response. To address these limitations, the HKUST team developed a novel image sensor based on vertical 1T’/2H-MoTe2 homojunctions. By combining narrow-bandgap 2H-MoTe2 with a high-quality Ohmic contact at the 1T’/2H interface, the team enabled a crossbar-array architecture capable of ultralow-power and near-infrared imaging. The work demonstrates how van der Waals integration can overcome the long-standing tradeoff between short channel length and large light-collecting area in next-generation image sensors.
The device performance was striking. With this design, the self-powered image sensor achieved a photoresponsivity of 4.6 A·W-1 and a detectivity of 5.8×1013 cm Hz1/2 W-1 at an optimized channel thickness of 23 nm. The sensor adopts a 10×10 crossbar array made of vertically stacked 1T’/2H-MoTe2/ITO devices, in which each 1T’/2H-MoTe2 homojunction sits at the intersection of two strip-shaped ITO electrodes. Notably, the entire array requires only 20 electrodes, greatly simplifying the integration process and reducing structural complexity compared with conventional pixel-addressing strategies. This compact architecture provides an efficient route toward scalable, low-power imaging systems operating from visible to near-infrared wavelengths.
Prof. Luo explained that the team realized the 1T’/2H-MoTe2 homojunctions through a two-step chemical vapor deposition process. In the resulting device, the Ohmic contact at the 1T’/2H-MoTe2 interface and the Schottky contact between 2H-MoTe2 and ITO generate an internal built-in electric field, allowing the photodetector to operate in a self-powered mode. By optimizing the 2H-MoTe2 thickness from sub-4 nm to 34 nm, the team identified 23 nm as the optimal channel length to balance resistance, depletion width, and light absorption for the best imaging performance. This strategy opens a promising route toward next-generation image sensors with high performance and ultralow energy consumption.
This project was a collaboration between HKUST, the Hong Kong Polytechnic University, the Chinese University of Hong Kong, and Beijing Institute of Technology. The findings were published in Matter under the title "Van der Waals-integrated crossbar arrays with adjustable atomic-scale channels for ultralow-power imaging."
