The continuous downscaling of MOSFETs for high-performance applications has made their reliability under harsh radiation environments a critical concern, particularly in advanced space, defense, and high-speed communication systems. Among various III–V compound semiconductors, indium arsenide (InAs) has emerged as a highly attractive channel material for nanoscale devices due to its narrow bandgap (0.36 eV), very high electron mobility (~30,000 cm2/V·s at 300 K), and superior electron saturation velocity. These properties make InAs quantum well MOSFETs capable of delivering enhanced drive current, low power-delay product, and excellent performance in ultra-scaled regimes compared to traditional silicon-based devices. However, the same narrow bandgap that benefits transport also makes InAs devices more vulnerable to radiation-induced effects, such as single-event transients (SETs), which can compromise device stability and reliability in radiation-rich environments. In this context, the present book chapter undertakes a detailed investigation of the SET response of InAs quantum well N-MOSFETs employing a raised source–drain architecture. The study focuses on devices with a fixed channel length of 14 nm, while the channel thickness is varied between 4 and 10 nm. The radiation environment is modeled using incident Neon, Krypton, and Xenon ions to capture the impact of different ion masses and energies. Furthermore, the groove angle (θ) of the device is systematically varied from 40° to 90° in order to identify the most radiation-hardened device configuration.