Self-Powered Broadband Computational Imaging Based on CdS/Ge 2D/3D Type-I Heterojunction Photodetectors

Abstract

The breakthrough in van der Waals heterojunction diodes composed of 2D and 3D materials for optoelectronic devices has paved the way for advancements in broadband optical imaging. However, fabricating traditional array-based imaging detectors with these materials remains challenging. Cadmium sulfide (CdS), a historically significant semiconductor material, has been extensively used in optoelectronic devices due to its remarkable photoelectric properties and chemical stability. Notably, a unique type-I heterojunction can be formed by combining 2D CdS, prepared through chemical vapor deposition, with the first-generation semiconductor germanium (Ge). His heterojunction photodetector exhibits outstanding photoelectric performance, achieving a responsivity of 54 mA W⁻¹ and a detectivity of 1.4 × 10⁹ Jones under zero bias, with a spectral response range spanning from 265 to 1550 nm. Herein, the CdS/Ge heterojunction photodetector with the emerging single-pixel Hadamard algorithm, addressing challenges in nonvisible imaging that conventional imaging systems traditionally encounter, is integrated. This approach facilitates low-sampling-rate image reconstruction across a broad spectral range and under scattering conditions. It is anticipated that this work will significantly contribute to future advancements in broadband imaging applications.