Ge Yang

Gallium oxide (Ga ₂ O ₃ ) is an emerging candidate for next-generation radiation detectors due to its ultrawide bandgap, high-temperature stability, and large breakdown field, making its radiation tolerance and defect behavior critical to advancing device performance. To investigate the mechanisms of radiation damage and microstructural evolution, β-Ga ₂ O ₃ samples were irradiated at the North Carolina State University PULSTAR reactor to neutron fluences up to ~10 ¹⁸ cm ⁻² at both room temperature and 700 °C using custom vertical irradiation ports that enable continuous exposure while allowing selective retrieval of samples at predetermined dose levels. Post-irradiation characterization using optical transmittance measurements and positron annihilation spectroscopy (PAS) revealed pronounced radiation darkening and reduced transmittance in room-temperature-irradiated samples, accompanied by increased positron lifetimes indicative of progressive defect accumulation. In contrast, samples irradiated at 700 °C exhibited minimal optical darkening and negligible changes in positron lifetime, suggesting that elevated temperature suppresses the formation or retention of neutron-induced defects. These results highlight a thermal threshold that strongly governs defect diffusion, recombination, and trapping behavior in β-Ga ₂ O ₃ , providing insight into pathways for enhancing its radiation resilience for nuclear and high-energy applications.

This work investigates the growth, structural characteristics, and proof-of-concept radiation response of methylammonium lead iodide (MAPbI3) single crystals for direct x-ray and γ-ray detection. Large, optically clear MAPbI3 single crystals were synthesized using a modified cyclic inverse temperature crystallization (ITC) approach, enabling repeated growth within a single precursor solution under controlled thermal conditions. The resulting crystals exhibited well-defined faceted morphologies with dimensions ranging from millimeters to centimeters and high structural quality. Schottky barrier photodetectors fabricated using these crystals exhibited high photosensitivity (3.68 × 105 μC Gy−1 cm−2), a low detection limit (0.0114 μGy s−1), and excellent linearity under x-ray and γ-ray irradiation. The results demonstrate that cyclic ITC provides a reproducible and material-efficient pathway for producing high-quality MAPbI3 single crystals suitable for direct ionizing radiation detection.

Gallium oxide (Ga2O3) has emerged as a promising material for high-power and radiation-tolerant electronics due to its ultra-wide bandgap and excellent thermal stability. In this study, single-crystal β-Ga2O3 was exposed to neutron irradiation for periods up to 300 h to investigate its structural, chemical, electronic, and mechanical response. Post-irradiation examination revealed that the material maintained its monoclinic crystal structure, with no evidence of phase transformation, elemental segregation, or significant bandgap alteration. Atom probe tomography and energy-dispersive spectroscopy confirmed uniform elemental distributions of Ga, O, and Fe, while high-resolution electron energy-loss spectroscopy indicated negligible changes in the electronic structure. Nanoindentation measurements showed an increase in hardness after irradiation, suggesting the formation of irradiation-induced defects and associated radiation-hardening. These findings demonstrate that β-Ga2O3 can withstand low-dose neutron irradiation while preserving its microstructural, chemical, and electronic integrity, highlighting its potential for robust, high-performance devices in extreme radiation environments.

Gallium oxide (Ga₂O₃) is distinguished in the electronics field for its ultrawide bandgap, high breakdown field, and transparency to visible and infrared light, making it highly attractive for sensor applications in harsh environments. This study investigates the evolution of defects in Ga₂O₃ under ion irradiation, annealing, and their combined effects, with a unique focus on in situ transmission electron microscopy (TEM) observations. We examined three electron-transparent Ga₂O₃ lamellas (samples A, B, and C) under distinct conditions: Sample A was subjected to Kr²⁺ ion irradiation up to 15.4 displacements per atom (dpa) at room temperature; Sample B was annealed in 100 °C increments up to 500 °C; Sample C underwent simultaneous annealing at 500 °C and ion irradiation. TEM provided detailed, real-time characterization throughout the experiments, offering unprecedented insights into defect dynamics. Our findings reveal the formation and growth of small black defects (SBDs), defect clusters, and dense dislocation networks under irradiation. The crystal structure remained stable during gradual heating, but combined irradiation and temperature effects accelerated defect formation and evolution. Notably, a phase transition from β to γ was observed during the irradiation-only experiment. The in situ and ex-situ TEM observations provide a novel and impactful perspective on the behavior of Ga₂O₃, contributing significantly to the understanding of its properties under extreme conditions. These insights pave the way for the development of more resilient Ga₂O₃ electronic devices, enhancing their performance and reliability in demanding applications.

A streamlined sample preparation method for nanomechanical testing is needed to improve the quality of specimens, reduce the cost, and increase the versatility of specimen fabrication. This work outlines an in-plane liftout focused ion beam (FIB) fabrication procedure to prepare electron-transparent specimens for in situ transmission electron microscopy (TEM) nanomechanical testing. Ion etching and electron backscatter diffraction (EBSD) techniques were used to lift out a [110] oriented grain from a neutron-irradiated bulk X-750 alloy. Careful control of voltages and currents ensured precision. Top surface thinning sweeps prevented resurfacing and redeposition while dog-bone geometries were shaped with a 1:4 gauge width-to-milling pattern diameter ratio. Nanotensile testing in the TEM with a picoindenter allowed for the estimation of an ultimate tensile strength of 2.41 GPa, and inspection revealed a high density of bubbles in the X-750 matrix. The proposed fabrication procedure is significant for preparing samples from radioactive materials, studying complex structures that are orientation-dependent, and analyzing desired planar areas.

— The all-inorganic lead free Cs2AgBiBr6 perovskite represents a highly promising environment-friendly radiation detector material. The first attempt to grow Cs2AgBiBr6 single crystals using the unique gel growth method is reported in this study. This technique enables controlled reagent diffusion in a gel medium at room temperature, fostering the growth of visible single crystals. It offers advantages over conventional methods, leading to fewer equilibrium and non-equilibrium defects and simplified execution. Interestingly, the as-grown crystals exhibited variations in size and colors within the gel matrix, indicating the influence of Bi solutes in Bi-poor and Bi-rich Cs2AgBiBr6 crystals. Once the crystals were confirmed by powder x

The dissemination of sensors is key to realizing a sustainable, ‘intelligent’ world, where everyday objects and environments are equipped with sensing capabilities to advance the sustainability and quality of our lives—e.g. via smart homes, smart cities, smart healthcare, smart logistics, Industry 4.0, and precision agriculture. The realization of the full potential of these applications critically depends on the availability of easy-to-make, low-cost sensor technologies. Sensors based on printable electronic materials offer the ideal platform: they can be fabricated through simple methods (e.g. printing and coating) and are compatible with high-throughput roll-to-roll processing. Moreover, printable electronic materials often allow the fabrication of sensors on flexible/stretchable/biodegradable substrates, thereby enabling the deployment of sensors in unconventional settings. Fulfilling the promise of printable electronic materials for sensing will require materials and device innovations to enhance their ability to transduce external stimuli—light, ionizing radiation, pressure, strain, force, temperature, gas, vapours, humidity, and other chemical and biological analytes. This Roadmap brings together the viewpoints of experts in various printable sensing materials—and devices thereof—to provide insights into the status and outlook of the field. Alongside recent materials and device innovations, the roadmap discusses the key outstanding challenges pertaining to each printable sensing technology. Finally, the Roadmap points to promising directions to overcome these challenges and thus enable ubiquitous sensing for a sustainable, ‘intelligent’ world.

A new 0D metal halide (TEP)InBr₄ is reported. Structural and electronic properties were studied. The fabricated X-ray detector using a (TEP)InBr₄ single crystal showed a detection sensitivity of 569.85 μC Gy⁻¹ cm⁻² at E = 100 V mm⁻¹.