Infrared Photodetector Fabrication by Femtosecond Laser-Engineered Black Silicon: A Comprehensive Review

Black Si (b-Si) synthesized via femtosecond (fs) laser processing has emerged as a pivotal candidate material for next-generation infrared (IR) photodetectors. Its unique hierarchical micro/nanostructures, in synergy with supersaturated impurity doping, enable dual core functionalities-broadband light trapping and sub-band gap absorption-which collectively extend the spectral response of Si-based devices from visible to near-infrared. Endowed with inherent advantages including complementary metal-oxide-semiconductor (CMOS) process compatibility, low-cost scalable fabrication, and industrial adaptability, b-Si provides a viable technical route to address the intrinsic limitations of traditional III-V and II-VI semiconductor materials, such as lattice mismatch-induced epitaxial defects, complex growth processes, and prohibitive production costs. This review systematically summarizes recent advances in fs laser-processed b-Si for IR detection, with a focus on three interrelated thematic areas: (1) the fundamental physical mechanisms governing enhanced light absorption, encompassing multiple scattering effects and impurity band-mediated sub-band gap transitions; (2) key performance optimization strategies, including precision morphology engineering, gradient impurity/co-doping protocols, and advanced post-processing techniques (e.g., heterostructure construction, plasmonic resonance enhancement, and atomic-layer-deposition-based surface passivation); (3) integration methodologies between b-Si and diverse photodetector architectures, such as planar/vertical p-n junctions, Schottky barrier diodes, and hybrid van der Waals heterostructures. Finally, the critical challenges restricting the practical deployment of fs laser-engineered b-Si are delineated, and prospective development directions are proposed-including CMOS-compatible mass fabrication, hetero-material integration for mid-wave IR extension, multispectral detection system design, and long-term stability enhancement via novel passivation strategies. This review aims to establish a comprehensive reference framework for rational design, performance optimization, and industrial translation of high-sensitivity, broadband, low-noise Si-based IR detectors.