Investigation of high-energy proton irradiation effects on carbon nanotube field-effect transistors

Abstract

This study systematically investigates the effects of 200 MeV proton irradiation on the electrical properties of carbon nanotube field-effect transistors (CNTFETs). Key device parameters, including the threshold voltage (Vth), transconductance (Gm), and subthreshold swing (SS), were quantitatively assessed to reveal the irradiation-induced degradation patterns. The results reveal a complex, dose-dependent variation in electrical performance. While the threshold voltage exhibits a monotonic negative shift with increasing dose, other parameters, such as SS, Gm, and contact resistance (Rc), show a non-monotonic response: they deteriorate at low fluences but subsequently recover or even improve at higher fluence. This behavior is attributed to the competition between two underlying mechanisms. At low fluence, the degradation is primarily driven by ionization energy loss, as confirmed by SRIM (Stopping and Range of Ions in Matter) simulations of the proton energy deposition profile. At high fluence, the analysis of hysteresis characteristics and contact resistance indicates that radiation-enhanced desorption of surface adsorbates and effective modulation of the Schottky barrier at the metal/CNT interface become the dominant factors, leading to partial performance recovery.