Three-dimensional diamond planar spiral detectors have emerged as promising tools for alpha and neutron detection, combining advanced materials science with innovative fabrication techniques. These detectors leverage the exceptional properties of diamond, such as its superior carrier transport and high radiation tolerance, which are pivotal for applications range from nuclear plant safety to environmental monitoring.
Researchers have developed these detectors utilizing nano-carbon networks (NCNs) embedded within thick 300 μm diamond substrates. The unique design involves two titanium/platinum/gold spiral electrodes connected to internal spiral NCN wall electrodes, extending 20 μm below the surface and strategically separated by 50 μm. Such configurations aim to address challenges posed by traditional detectors, which often degrade under intense radiation exposure.
"The incorporation of internal NCN 'wall' electrodes within the diamond spiral detectors enhanced the charge collection efficiency (CCE) of the detectors by up to 9%," said the authors of the article. This improvement is significant as it allows the detectors to exhibit nearly 100% charge collection efficiency and rise times below 1.35 nanoseconds, ensuring rapid and accurate detection of radiation.
Historically, diamond detectors have been utilized for their low background noise and fast signal response. Yet, traditional designs often faced limitations, especially when detecting high-energy alpha particles. Conventional Metal Insulator Metal (MIM) configurations required extensive biasing and high-quality diamond substrates to achieve satisfactory performance. Alpha particles have relatively short penetration depths, making it challenging to design effective detectors.
To innovate, the research team employed femto-second lasers to write complex conductive tracks within the diamond structure. By building up layer by layer, the team created NCN wall electrodes starting 20 μm below the surface, forming the core of their novel spiral detector design. The results of these efforts yielded highly reliable detectors without the fragility associated with thin diamond membranes often used previously.
Current-Voltage measurements, Raman spectroscopy, alpha spectroscopy, and transient current tests using the radioactive Americium-241 source confirmed the effectiveness of the new design. The fabricated spiral detectors were shown to exceed the performance of existing reference MIM detectors by significantly improving CCE.
The approach yielded charge collections of up to 54.4 ± 0.9 femtocoulombs (fC) for the NCN-spiral detectors when operated under optimal field conditions, which also marked a significant 25-30% improvement compared to earlier designs. Notably, they achieved comparable performance to traditional detectors at significantly lower operating biases.
One contributing factor to the effectiveness of these new detectors is their structure. The arrangement of the NCN electrodes aids in projecting electric fields throughout the detector space, facilitating more efficient charge collection processes. When subjected to alpha radiation, the detectors were primed for over 13 hours, maximizing their efficiency and performance, which is typical for detectors undergoing extensive alpha exposure.
The study outlines the promising features of this advanced detector technology, emphasizing the potential for practical applications, especially in real-time monitoring scenarios such as nuclear facilities and environmental assessments. Future iterations could explore vertical designs to optimize packaging and durability. Such innovations may lead to detectors more resistant to external radiation and easier to deploy within harsh environments.
These three-dimensional planar detectors not only represent significant advancements for radiation detection technology but may also open new pathways for utilizing cheaper, lower-quality diamonds without compromising performance. This aspect could expand the accessibility and cost-effectiveness of radiation detection methodologies.
Overall, the fabricated diamond spiral detectors exemplify how innovative engineering solutions can vastly improve existing technologies, indicating potential for high functionality within the specialized field of radiation monitoring.
Researchers anticipate continued refinement and exploration of alternative geometries to optimize these detectors for future high-energy applications. The promise they hold could revolutionize radiation detection, fostering increased safety and efficiency across multiple sectors.