Fundamentals of Ionizing Radiation

Abstract

Ionizing radiation ($\gamma$-ray, X-ray, high-energy UV-ray, heavy ions, etc.) affects electronic circuits and living beings. It has been a significant concern for critical reliability applications like medical, aviation, space missions, and high-energy physics experiments considering safety and quality assurance. The radiation research community, including physicists, medical researchers, nuclear reactor, and accelerator engineers, has long been working on analyzing the effects of ionizing radiation. Over the past few decades, several studies about the sources of radiation and the physics of radiation effect mechanisms [7, 8] have helped the development of numerous radiation sensors. As silicon technology evolved, the downscaling of modern CMOS technologies has made MOS devices less sensitive to cumulative radiation dose effects [20]. As the gate oxide thickness has reduced, the rate of radiation-induced hole trap** has gone down. Also, the generation of interface trap charges has decreased notably due to electron tunneling [23], and subsequent neutralization of holes [24]. On the other hand, for scaled-down CMOS technologies, the critical charge required to cause a SEE has reduced significantly [31, 32]. As a result, the probability of SEEs in devices with smaller feature sizes has increased. Considering the wide variety of fields in the radiation environment, this chapter (Parts of this chapter were adapted from the published open-access article in MDPI, Radiation journal [6].) briefly discusses the fundamentals of ionizing radiation by mentioning the sources of ionizing radiation and briefly explaining the underlying mechanisms of various radiation effects. It also presents an overview of modern methods and devices developed for measuring the level of radiation and its effects on electronic instruments. Furthermore, it discusses various mitigation strategies for radiation-induced effects focusing on radiation-hardened-by-design (RHBD) techniques.