Radiation-tolerant sensors and detectors are critical components in nuclear and space environments, where exposure to high-energy particles and ionizing radiation can degrade performance or cause catastrophic failure. These sensors must maintain functionality under extreme conditions, requiring careful material selection, innovative design, and effective shielding strategies. Key applications include real-time radiation monitoring, imaging in harsh environments, and neutron detection for nuclear safety.

Photodiodes are widely used for radiation detection due to their fast response and high sensitivity. Materials such as cadmium telluride (CdTe) and gallium arsenide (GaAs) are preferred for their high atomic number and radiation hardness. CdTe, with its wide bandgap (1.44 eV at 300 K), exhibits low leakage currents and high stopping power for gamma rays, making it suitable for space-based X-ray and gamma-ray detection. GaAs, with a bandgap of 1.42 eV, offers excellent electron mobility and resistance to displacement damage caused by protons and neutrons. Silicon photodiodes, while less radiation-hard, are often used in lower-dose environments due to their cost-effectiveness and mature fabrication processes. To enhance radiation tolerance, designers employ guard rings, epitaxial layers, and defect engineering to mitigate charge trapping and recombination effects.

CMOS image sensors face significant challenges in radiation-rich environments, particularly in space missions where total ionizing dose (TID) and single-event effects (SEE) can degrade performance. Radiation-induced dark current, pixel noise, and latch-up events are common failure modes. Hardened CMOS technologies incorporate techniques such as enclosed layout transistors (ELT) to reduce leakage, silicon-on-insulator (SOI) substrates to minimize parasitic currents, and redundant circuitry to prevent single-event upsets. Backside-illuminated (BSI) sensors with thin substrates reduce charge diffusion and improve quantum efficiency in high-radiation conditions. Innovations like in-pixel dose monitoring and adaptive readout circuits enable real-time radiation assessment, crucial for missions in planetary exploration and satellite imaging.

Neutron detectors are essential for nuclear reactors, radiation safety, and scientific research. Traditional helium-3 tubes face supply shortages, driving the development of solid-state alternatives. Boron-10-enriched semiconductors and lithium-indium diselenide (LiInSe2) are emerging materials for direct neutron conversion, offering compact form factors and high sensitivity. Diamond-based detectors, with their ultra-wide bandgap (5.47 eV), exhibit exceptional radiation hardness and fast response times, suitable for high-flux neutron detection. Scintillator-coupled photodiodes using materials like gadolinium oxysulfide (Gd2O2S) or europium-doped lithium fluoride (LiF:Eu) provide another approach, converting neutron interactions into detectable light pulses.

Material selection is a primary factor in radiation-hardened sensor design. Wide and ultra-wide bandgap semiconductors such as silicon carbide (SiC) and gallium nitride (GaN) are increasingly adopted due to their high displacement energies and low thermal noise. SiC, with a bandgap of 3.26 eV for the 4H polytype, demonstrates superior resistance to displacement damage from protons and heavy ions, making it ideal for high-energy physics experiments. GaN’s strong atomic bonding and high breakdown field (3.3 MV/cm) enable stable operation in extreme radiation environments, particularly for high-frequency and power devices. For neutron detection, boron carbide (B4C) coatings and gadolinium-based absorbers enhance conversion efficiency while minimizing gamma-ray interference.

Shielding strategies are equally critical in preserving sensor functionality. Passive shielding using high-density materials like tungsten or lead reduces gamma and X-ray exposure but adds mass, a significant constraint in space applications. Active shielding with magnetic fields deflects charged particles but requires substantial power. Multilayer shielding combining hydrogen-rich polymers (e.g., polyethylene) with metals effectively attenuates both neutrons and gamma rays while minimizing weight. In semiconductor detectors, on-chip shielding through buried layers and guard rings reduces charge collection from secondary particles generated by radiation interactions.

Real-time radiation monitoring has seen significant advancements with the integration of smart sensing systems. On-chip dosimeters using floating-gate transistors or pinned photodiodes provide continuous dose measurement without external components. Fiber-optic sensors employing radioluminescent materials like aluminum oxide (Al2O3:C) offer distributed monitoring in nuclear facilities, with optical signals immune to electromagnetic interference. Emerging technologies such as plasmonic sensors and quantum dot spectrometers enable high-resolution radiation mapping with minimal power consumption.

Innovations in radiation-tolerant sensors continue to push the boundaries of reliability and performance. Monolithic integration of sensing and processing circuits reduces system complexity and improves noise immunity. Self-calibrating detectors using reference radiation sources ensure long-term accuracy in harsh environments. Machine learning algorithms analyze sensor data to predict degradation and optimize shielding configurations dynamically. These advancements are critical for future missions to high-radiation zones, such as Jupiter’s magnetosphere or lunar surface operations, where conventional electronics would fail rapidly.

The development of radiation-hardened sensors remains a multidisciplinary effort, combining materials science, device physics, and systems engineering. As space exploration expands and nuclear applications grow more complex, the demand for robust, high-performance detectors will only increase. Future research will focus on novel materials like topological insulators and hybrid perovskites, as well as advanced fabrication techniques to further enhance radiation tolerance without compromising sensitivity or speed. The ongoing evolution of these technologies ensures that sensors will continue to operate reliably in the most challenging environments.