Quasi-Homojunction Based on 1D-Chained Alloyed Sb<sub>2</sub>Se<sub>3</sub> for High-Performance Broadband Photodetection and Matrix Imaging.

Gao, Ruisi; Chen, Xinyi; Wang, Xinyue; Hu, Hao; Yang, Feifan; Lin, Ling; Zhou, Lin; Liu, Danling et al. · Nano Lett · 2025

basic_science · Level V

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Abstract

Junction-based photodiodes play a crucial role in integrated devices due to their compactness and efficient rectification. However, three-dimensional (3D) semiconductor heterojunctions suffer from high interface defects caused by lattice mismatch, while one-dimensional (1D) semiconductors feature large interchain gaps that alleviate lattice matching requirements and provide high strain relaxation, making them highly promising for homojunction construction. Herein, a quasi-homojunction is constructed via in situ Bi doping in 1D Sb<sub>2</sub>Se<sub>3</sub>. Compared to uniform film photodetectors, the quasi-homojunction-based photodetector exhibits a low dark current (4.8 nA cm<sup>-2</sup>), high light current (62.2 μA cm<sup>-2</sup>), high external quantum efficiency (35.5%@2.73 nW cm<sup>-2</sup>), and fast response speed. Furthermore, the photodetector is monolithically integrated on the thin-film transistor readout circuit for short-wavelength infrared imaging applications, demonstrated in a 64 × 64 pixel array. Moreover, the detectors exhibit a broadband detection from X-ray to near-infrared, showing potential application for image fusion. This work provides a novel strategy for broadband photodetectors and integration.