Cascade engineering suppresses background noise to boost the sensitivity of X-ray imaging detectors

A detection technology that can create sharp images from ultra-low X-ray doses could improve the safety of X-ray medical imaging. The invention achieves high sensitivity using a novel arrangement of perovskite single crystals as X-ray detecting materials.

Although X-ray machines remain a key form of medical imaging, X-rays are a high energy form of ionizing radiation and high doses are associated with an increased risk of cancer.  Keeping X-ray exposure to within safe limits curtails medical use.

An intense search is underway to identify materials that could increase the sensitivity of X-ray detectors, enabling high-quality medical images using very low X-ray doses.

“In recent years, many perovskite single crystal materials have demonstrated excellent X-ray detection performance,” says KAUST researcher Xin Song, a member of Omar Mohammed’s research group, who led the research.

When an X-ray photon strikes a perovskite semiconductor crystal, it generates a pair of electric charges, one positive and one negative. When these charges reach electrodes at the perovskite edges, they create a photocurrent from which X-ray images can be generated.

To push the performance of perovskite X-ray detectors further, the team has targeted the materials’ ‘dark current’. “The dark current of an X-ray detector semiconductor refers to the electrical current that flows through the device when it is not exposed to X-rays,” says Song. Dark current is primarily caused by heat-generated charge carriers and leakage currents within the device, she says.

Read more at Kaust Discovery.