Unrecovered ion-irradiated damage after thermal annealing in graphene field effect transistors

Abstract

Irradiation effects in graphene-based devices are crucial for applications of carbon-based devices utilized in aerospace and other radiation harsh environments. In this work, the deteriorated electrical properties of graphene field effect transistors (GFETs) induced by swift heavy ions (SHIs, 1.8 GeV Ta) and evolution of the defects in device materials after irradiation and thermal annealing have been investigated. The SHIs induced defects in graphene result in the increase of resistance and decrease in carrier mobilities. Thermal annealing at 110 °C could improve the carrier mobility at smaller scale that can be ascribed to the degassing effect. The defects in graphene were unrepairable after annealing at 110 °C. At higher temperature (e.g., 500 °C), the graphene structure was further damaged as a result of the compressive strain induced by thermal contraction of the SiO2 layer. The evolutions of graphene and SiO2 surface morphologies with increasing annealing temperature were studied by Atomic Force Microscopy investigations. After irradiation, the weakened lattice structure order of the Si layer and change of the SiO2/Si interface morphology were confirmed. It was also shown that the damage in SiO2/Si interface did not recover even after the high temperature (e.g., 1100 °C) annealing.