Objective Silicon-based photodetectors have established themselves as indispensable components in modern integrated optoelectronics, offering compelling advantages, including low fabrication costs and seamless compatibility with complementary metal-oxide-semiconductor (CMOS) processing infrastructure. These attributes have enabled their widespread deployment across consumer electronics, data center optical interconnects, and machine vision systems. However, silicon’s fundamental physical limitation imposes a strict cutoff wavelength of approximately 1.1 μm, rendering it inherently insensitive to the technologically critical infrared communication windows centered at 1.31 μm and 1.55 μm, as well as the extended short-wave infrared (SWIR) spectrum beyond 2 μm. This intrinsic “bandgap bottleneck” fundamentally constrains silicon photonics from fully addressing the escalating demands of next-generation applications, including fifth-generation wireless communications, light detection and ranging for autonomous vehicles, artificial intelligence-enhanced vision systems, night-vision surveillance, and environmental monitoring. Although traditional alternatives, such as germanium-based or III–V compound-semiconductor detectors, offer extended infrared response, they present significant drawbacks, including incompatibility with CMOS processes, high material costs, and integration complexity. Against this technological landscape, the emergence of deep-level impurity hyperdoping represents a promising approach to overcoming silicon’s spectral limitations while preserving its manufacturing advantages. This review provides a comprehensive and systematic examination of this transformative materials platform, offering critical insights into the fundamental mechanisms, fabrication methodologies, material characteristics, and device performance metrics that define the current state and future trajectory of hyperdoped silicon-based infrared photodetection technology.

Methods The fabrication of hyperdoped silicon materials fundamentally relies on two complementary technological pillars: ion implantation for supersaturated impurity incorporation and subsequent ultrafast thermal processing for lattice recrystallization and electrical activation. Ion implantation enables precise control over dopant species, concentration profiles, and penetration depths, facilitating the introduction of deep-level impurities at concentrations far exceeding equilibrium solubility limits. The choice of impurity species critically determines the optoelectronic properties of hyperdoped silicon, with two principal categories demonstrating particular promise. Chalcogen elements introduce deep-level donor states that form well-defined intermediate bands (IBs) within silicon’s bandgap, enabling sub-bandgap infrared absorption. Transition metals similarly create deep-level states, though their electronic configurations and resulting band structures differ substantially from those of chalcogen-doped systems. The ultrafast annealing step, typically implemented through either pulsed laser melting (PLM) or flash lamp annealing (FLA), enables impurity redistribution and substitutional incorporation during liquid-phase epitaxial regrowth, and suppresses thermal diffusion that would otherwise lead to impurity segregation or precipitate formation. PLM offers nanosecond-scale processing with precise spatial control and a minimal thermal budget, while FLA provides larger-area uniformity and compatibility with batch processing. Both techniques successfully preserve the supersaturated impurity concentrations essential for strong sub-bandgap absorption while restoring crystalline quality and minimizing residual implantation damage.

Results and Discussions The IB formed by deep-level impurities fundamentally alters silicon’s optical properties, introducing sub-bandgap absorption coefficients reaching 10⁴ cm⁻¹ in the near-infrared and extending sensitivity well beyond 2 μm. Photodetectors fabricated from hyperdoped silicon materials have demonstrated impressive room-temperature performance. Te-hyperdoped silicon photodiodes achieve specific detectivities of 3.2 × 10¹² cm·Hz^1/2·W⁻¹ at 1.0 μm and 9.2 × 10⁸ cm·Hz^1/2·W⁻¹ at 1.55 μm, with response times of 39-42 μs. Ag-hyperdoped silicon detectors exhibit responsivities of 504 mA/W at 1310 nm and 65 mA/W at 1550 nm under −3 V bias, with external quantum efficiencies of 0.48 and 0.052 respectively, and response times of approximately 12-16 μs. Titanium-hyperdoped devices demonstrate a responsivity of 34 mA/W at 1.55 μm with a specific detectivity of 1.7 × 10⁴ cm·Hz^1/2·W⁻¹ at 660 Hz. Au-hyperdoped silicon extends room-temperature photoresponse to 2.2 μm. Critically, these devices maintain full compatibility with standard CMOS fabrication processes, suggesting straightforward pathways toward monolithic integration. The working mechanism involves IB-assisted sub-bandgap absorption followed by gain generation through carrier-lifetime disparity; that is, photogenerated minority carriers are temporarily trapped by deep-level states, which extends their effective lifetime far beyond the electrode transit time and enables multiple majority-carrier injections per absorbed photon, providing the fundamental origin of high photoconductive gain. However, ion implantation-induced lattice defects lead to elevated dark current densities, and external quantum efficiency remains substantially below commercial detectors, fundamentally limiting sensitivity in photon-starved applications. The thermal stability of the IB also remains a concern, as high-temperature processing can lead to impurity precipitation and degradation of optoelectronic properties.

Conclusions Deep-level impurity hyperdoping via ion implantation and ultrafast thermal processing has emerged as a transformative materials platform that fundamentally addresses silicon’s intrinsic bandgap limitation while preserving its manufacturing advantages. The IB formed by supersaturated chalcogen or transition metal impurities enables efficient sub-bandgap photon absorption, effectively extending silicon-based photodetector sensitivity into technologically critical infrared spectral regions. The combination of precise ion implantation with nanosecond-scale PLM or millisecond-scale FLA successfully achieves and maintains the nonequilibrium impurity concentrations essential for IB formation. To advance practical applications, future research should pursue a systematic path encompassing device architecture optimization, material system engineering, and dimensional innovation. First, device architecture optimization represents the foundational path toward performance breakthroughs. The design of CMOS-compatible lateral p-i-n photodiode arrays with ultrathin hyperdoped active layers and interdigitated electrodes can enhance carrier collection efficiency. Integration of wide-bandgap blocking layers and surface passivation coatings can effectively suppress dark current by orders of magnitude. Second, material system engineering through heterojunction integration with two-dimensional materials offers new pathways for performance enhancement. Combining hyperdoped silicon with transition-metal dichalcogenides or graphene enables band structure engineering and interfacial-field-driven carrier separation. However, lattice mismatch and interface state issues must be systematically addressed through optimized passivation strategies. Notably, recent studies demonstrate that even without hyperdoping, graphene integrated with microstructured silicon can achieve broadband infrared response through potential fluctuation engineering, highlighting alternative pathways that complement the hyperdoping approach. Third, extending hyperdoping from bulk silicon to low-dimensional nanostructures opens new frontiers for exploring quantum confinement effects. Silicon nanowires and nanomembranes offer exceptional light confinement, shortened carrier collection paths, and potential for monolithic integration with on-chip photonic circuits, though challenges in conformal doping and thermal budget management for non-planar structures remain unresolved. As these challenges are systematically addressed through coordinated experimental and theoretical efforts, deep-level impurity-hyperdoped silicon is poised to emerge as a foundational technology for next-generation infrared optoelectronics, enabling cost-effective, CMOS-compatible, room-temperature infrared detection for communications, sensing, imaging, and security applications.