Displacement damage effects of low-energy gallium ion irradiation on single-walled carbon nanotube field-effect transistors

The displacement damage (DD) effects induced by low-energy gallium ions (Ga⁺) on single-walled carbon nanotube field-effect transistors (SWCNT FETs) are investigated in this study. Exposure to 5 keV Ga⁺ irradiation resulted in significant changes in the Raman spectra and electrical properties of the devices. The key finding reveals a strong heavy-ion energy dependence of displacement damage (DD): the displacement damage dose (D_d) induced by 5 keV Ga⁺ irradiation is nearly three orders of magnitude higher than that induced by 2225 MeV xenon ions (Xe⁺). By integrating Raman spectroscopy, electrical characterization, and TRIM simulations, we demonstrate that low-energy heavy ions deposit substantially more energy via non-ionizing energy loss (NIEL) processes within the SWCNT and gate oxide layers compared with high-energy ions. This enhanced energy deposition generates more atomic displacements and vacancies, which significantly degrade both the conductivity of the SWCNT channel and the insulating properties of the gate oxide. These findings provide critical insights into the impact of low-energy ion irradiation on SWCNTs and contribute to a deeper understanding of SWCNT FET behavior in radiation environments.